Malcolm 'Mal' Reynolds was the captain of the Firefly-class transport ship Serenity. During the Unification War, Mal fought for the Independents and was the highest ranking Browncoat to participate in and survive the Battle of Serenity Valley. Mal was born on September 20, 2468, and was brought up on a ranch in Seven Pines Pass on the planet Shadow. Raised by his mother and "about 40 hands," Mal apparently received a fairly decent education growing up. Though Mal usually seems more practical than intellectual, he occasionally surprised his friends by displaying familiarity with a wide range of literature varying from the works of Shan Yu, a psychotic dictator, to poems by Samuel Taylor Coleridge. He, however, has no idea "who" Mona Lisa was. Mal volunteered for the Independents army during the Unification War against the Alliance, gaining the rank of sergeant during that time. His second-in-command Zoë Alleyne Washburne was by his side for most of the war, surviving many dangerous conflicts with him, such as the Battle of Du-Khang in 2510 and a long winter campaign in New Kasmir where he commanded a platoon. Mal was also involved in the ground campaign during the Battle of Sturges, which according to Badger was the "bloodiest and shortest battle in all the war", although Mal considered it a distant second. Mal fought in many more battles, but the turning point for him and the Independents came with their physical and emotional defeat at the Battle of Serenity Valley on the planet Hera.In the aftermath of the war, Mal saw a space-faring life as an escape from his past battles. To this end, Mal acquired his own ship, an old, broken and not flight-worthy 03-K64 Firefly-class transport whose previous owner was a man named Captain Harbatkin (and he never got around to changing the registration papers). He promptly named the ship Serenity. On board Serenity and during his various travels, Mal continued to wear his brown coat and wielded a standard issue officer's pistol, a Liberty Hammer, as his weapon of choice, a gun which he has had since the war and had modified extensively.

Zoë Alleyne Washburne was a Browncoat born February 15, 2484, "Vesselside". Zoë served in the Unification War under Sergeant Malcolm Reynolds for two and a half years, and was one of the few to survive the Battle of Serenity Valley. Zoë continued under his command on his spaceship, Serenity, as first mate, and was the wife of pilot Hoban Washburne. A loyal second-in-command and a tough, deadly fighter, Zoë was the only member of Mal's crew to regularly call him "sir", while taking orders as if receiving them from a superior officer.

Zoë was born Vesselside (meaning "aboard a spaceship") on February 15th, 2484. Nothing else is known about her upbringing. She fought on the side of Independence in the Unification War, a part of the 57th Overlanders Brigade. At the time of the Battle of Serenity Valley, Zoë had attained the rank of Corporal. Along with Sergeant Malcolm Reynolds, she was the only other survivor of their platoon in the seven week long battle. After the war, she and Mal were left for two weeks in the aftermath of Serenity Valley before being placed into camps for war crimes. Not long after, the Alliance decided they did not want any further conflict with the "Browncoats" and finally freed the war camp prisoners. Unlike Mal, Zoë was career military (meaning she worked in the military as her permanent job), and was often more calm in dangerous situations. Mal often thought with his heart, while Zoë usually thought with her head. Regardless, Zoë followed all orders from Mal, although often with a degree of advice or concern. After the war, Zoë joined up with the Dust Devils, a "terrorist" organization which continued to fight against the now Peacekeepers of the Alliance. After the war and her stint as a Dust Devil, Zoë joined Mal aboard Serenity, though she was skeptical of his plan at first, telling him the ship was a "death trap." The two found themselves hunted by the Unificators.Later, Zoë married Serenity's pilot Hoban "Wash" Washburne less than a year after he joined the crew, though she did not immediately like him when she met him. In "Out of Gas" we see Zoë's initial reaction to Wash in a flashback, in which she tells Mal, "I don't like him...just something about him bothers me" — maybe it was his disturbing moustache? Although Zoë and Wash worked a very dangerous sort of lifestyle, they managed to retain a rather happy marriage. Wash at times grew jealous of Zoë's close relationship with Mal, but later managed to get past it. During the events of Serenity Wash was killed. Heartbroken, Zoë and the rest of the crew built a memorial for her husband on Mr. Universe's moon.

Hoban "Wash" Washburne was the pilot of Serenity, a smuggling ship captained by Malcolm Reynolds. He was married to the ship's first mate, Zoë Alleyne Washburne.

Raised on a planet with pollution so thick the stars were not visible, Wash became a pilot in part to see the sky beyond his home. Wash was second in his class. Mr. Universe, Wash' friend in flight school, was top of the class, since he hacked the records. In order to buy Wash's silence (and save himself from a threat of bodily injury at the hands of Wash), Mr. Universe offered Wash his services whenever they were needed. Wash then traveled widely, visiting odd worlds where, for example, juggling goslings was the principal form of recreation. His skills as a pilot grew, and by the time Wash met Malcolm Reynolds, his reputation had grown to the point where he was actively courted by multiple captains in search of a good pilot (Mal tells Zoë that Wash has a list of recommendations "as long as [his] leg" when Zoë expresses her dislike of Wash). Wash accepted Mal's offer, and in the course of time, fell in love with and eventually married Reynolds' second-in-command, Zoë. This pairing was especially ironic, given that Zoë's first impression of Wash was one of immediate dislike and distrust.The two had a passionate and strong relationship, despite Wash's occasional concern over Zoë's strong personality and her tendency to assume the more aggressive, traditionally male role in the marriage, a concern compounded by Zoë's fierce loyalty and devotion to Mal. However, he does prove his loyalty when Saffron, a young woman posing as Mal's wife in order to take over the ship, attempted to seduce him by telling him the myth of the Earth-That-Was and how the stars joined it. He denied her, saying he had a "beautiful wife who can kill me with her pinky."Wash died when a harpoon launched by a Reaver ship impaled him, killing him instantly. His shipmates erected a memorial to him on Mr. Universe's moon. River Tam took up his duties as pilot of Serenity (under the supervision of Reynolds); as a tribute to Wash the collection of toy dinosaurs remains on the pilot's station of the bridge.

Inara Serra is a Companion who leases a shuttle from Captain Malcolm Reynolds and travels with Serenity's crew.

Inara, born in the late 25th century on Sihnon, is a Companion, a high-society courtesan licensed by the Union of Allied Planets. In Alliance society, Companions are part of the social elite, often accompanying the wealthy and powerful. They have considerable ritual and ceremony surrounding their services, which appear to extend beyond sex to nurturing psychological and emotional well being.

Inara was a rising member of Companion House Madrassa, possibly in contention for house priestess, when she suddenly and inexplicably left to travel the outer Rim. She has suggested that she "wanted to see the universe". In reality, the decision to leave was not entirely her own. During the Unification War, Inara had a client who was a secret informant for the Independents. During one of their sessions, the client let slip information about a planned major offensive against the Alliance. Inara, hoping to prevent bloodshed, alerted the authorities to the plot, and disclosed the location of the Browncoat's base on Fiddler's Green. The base, which housed both soldiers and refugees, was soon destroyed by Alliance forces. The priestess of House Madrassa discovered that Inara had broken the sacred rule of confidentiality by alerting the authorities. Inara was asked to leave House Madrassa; she would keep her Companion status but could never return home.

Less than a year before the events of "Serenity" (the pilot episode of Firefly), she contracted with Malcolm Reynolds, captain of spaceship Serenity, to lease one of its shuttles for transportation, living space, and workspace. This provides Inara with some mobility independent of Serenity, and Malcolm with some respectability that helps open doors in the marketplace that he might not otherwise achieve as an ordinary smuggler. Despite Mal's dislike of her profession (expressed in the episode "Shindig"), as well as by telling him during their first meeting (in flashback in the episode "Out of Gas") that she had supported Unification (see Unification Day), she and Mal have an unacknowledged attraction to each other. Complications due to this growing attraction cause her to briefly leave Serenity and take up teaching at a training house on one of the Rim planets. Mal and Inara have been shown to share certain traits with each other, as pointed out by Nandi during "Heart of Gold", the most prominent being that they both hate complications. The first edition of the comic "Leaves on the Wind" shows Mal and Inara in a loving embrace, hinting they might have finally gotten together. Later on, in the novel itself, they are found bickering as usual which finally leads to the consummation of their relationship in Mal's bunk. Their casual way of going about it suggests that Mal and Inara have been physically intimate for quite a while since the nine month gap between "Serenity" and "Leaves on the Wind".

Inara has a number of frequent clients throughout the Allied worlds, and takes both female and male clients, although most of her clients are male.

Inara appears to be at least somewhat adept at swordplay ("Shindig"). In the movie Serenity, it is shown that she also may have been trained somewhat in the martial arts, and is skilled with a bow and arrow, apparently preferring them over firearms.

Jayne Cobb, also known as the "Hero of Canton," was a mercenary who worked for Captain Malcolm Reynolds, aiding him on smuggling jobs aboard Serenity .

Jayne was a hired gun from Caliban who did not fight on either side in the Unification War. He met up with former Independence fighters Malcolm Reynolds and Zoë Alleyne Washburne when his gang tried to rob them. Noting Jayne's skill in tracking them, coupled with him learning how much Jayne was making with the current gang, Mal offered him a larger share of heists and his own bunk, and so Jayne shot one of his own companions and joined up with Mal instead, calmly asking, "How big a room?"

Jayne was good in a fight, and acted before he thought on many occasions. He was also somewhat thuggish and cruel; when arguing with Mal, he was not above insulting Mal's leadership skills by bringing up the events of the Battle of Serenity Valley, a highly sensitive subject for Mal. Although he often appeared to be somewhat stupid, he had his own peculiar wit. He had played successful jokes on the more intellectual Simon Tam (for instance, tricking Simon, who harbored an excessive fear of the vacuum of space, into putting on a spacesuit to board a pressurized ship). Jayne also had a keen sense of danger and was often the first to raise an accurate warning about impending peril.

Jayne kept a large arsenal in his bunk on Serenity. He had named his favorite and most powerful gun, a Callahan full-bore auto lock with customized trigger double cartridge thorough gauge, Vera. He acquired it after killing the previous owner, one of six assassins trying to kill him. After packing Vera into an oxygenated spacesuit so he could fire through outer space, Jayne preserved Serenity by disabling a carrion house (he also took care to kill the scrappers by shooting out their window, too). Jayne frequently carried a handgun based on a LeMat Percussion Revolver, and later carried a rifle named Lux .

Kaywinnet Lee "Kaylee" Frye is Serenity's mechanic. She is an exceptional engineer and has a natural intuition for machines, despite her lack of formal training. She is kind, trustworthy, sees the best in people, and is known as the "Heart of Serenity."

Kaylee had apparently always had an affinity with machines. On her home planet, she would often assist her father in repairing things. Kaylee joined the crew of Serenity when its captain, Malcolm Reynolds, interrupted her and Bester having sex in Serenity's engine room.At the time, Bester was Serenity's mechanic. However, when Bester incorrectly informed Mal that the ship could not be fixed, Kaylee quickly proved him wrong by diagnosing the problem and repairing the grounded Serenity. Impressed with her mechanical ability, Mal immediately offered her Bester's job. Kaylee happily accepted, and left her family (and Bester) behind to join the crew. Kaylee was shot in the stomach by the Alliance agent Lawrence Dobson. Simon Tam used her injury as a bargaining chip to be allowed to remain on Serenity with his sister, River. While Simon tended to Kaylee, Jayne Cobb was huddled on the catwalk outside of the infirmary watching the surgery. Earlier, Jayne had been banished from the dinner table for making lewd comments about her obvious attraction to Simon, thus humiliating her in front of Simon while leaving Simon himself very embarrassed.And yet, his obvious concern emphasized her importance to him and implied how deeply the other members of the crew care about her—although Jayne would still embarrass her later by making fun of her attraction to Simon, usually right in front of Simon. Simon Tam later confessed his feelings for her, which she reciprocated. The two finally consummated their relationship; Kaylee and shirtless Simon kissed each other passionately before sinking into her quarters, with River peeking in wide-eyed from an overhead hatch.

Simon Tam gave up his life as a top trauma surgeon on Osiris, a central planet, in order to rescue his little sister, River Tam, from an Alliance academy, becoming a wanted fugitive in the process. He now practices aboard Serenity as the ship's doctor and attempts to heal River.

Simon was born in late November, c. 2490 to Gabriel and Regan Tam, and raised on Osiris, a Core World planet with major Alliance ties. Simon supported Unification, the issue that sparked the eponymous War of Unification. He was young at the time of the war however, and may have been easily swayed by Alliance propaganda.

Much to the pleasure and possible insistence of his father, Simon entered medical school c. 2507, and was accepted into "MedAcad", the best Medical Academy, on Osiris, presumably the University of Osiris. Simon graduated in the top 3% of his class, and promptly moved onto a medical internship, which he completed in a mere eight months (as opposed to a year), and is licensed to practice medicine.

Despite his normal rigid persona, Simon later tells Kaylee Frye, engineer of Serenity, that after he and his fellow doctors officially became surgeons, they imbibed quite a large amount of sake, and ended up naked on a statue of Hippocrates. There are also rumors that Simon began singing the National Anthem, from which he either managed to talk or pay his way out of the Alliance telling his father. Simon admits that he is quite "fuzzy on details" regarding this story.

While onboard Serenity, the Pilot Wash realizes a beacon has been sent to the Alliance, and Captain Malcolm "Mal" Reynolds believes that it is Simon – a possible undercover agent – who has sent it out. In the ensuing conflict, they realize that Simon is not a fed, but Lawrence Dobson, another passenger, is. Dobson, in an attempt to gain control of the ship and capture the "fugitives" on board, and shoots Kaylee Frye in the stomach. As Simon is the only doctor on board, he alone has the means to save her, and uses this fact to make sure Mal Reynolds does not hand Simon and River over to the Alliance. Mal agrees only out of concern for Kaylee and resents most heavily anyone exerting power over him aboard his own ship. After Simon has done all he can for Kaylee, Mal decides to find out what Simon had in his crate. Mal opens it up, finding Simon's sister, River Tam.

Because of Simon and River's need to stay on the move in order to outpace the Alliance, Mal Reynolds offers Simon a job as doctor on the Serenity, and Simon accepts.

Simon soon settles into life on the ship, spending most of his time caring for River and attempting to figure out exactly what the Alliance did to her. The Tams remain below Alliance radar, despite some close calls, notably, the boarding of the ship in "Bushwhacked". It was revealed during this particular scrape that Simon has a phobia of being in empty space, likely due to the fact that he spent most of his life planet-side.

From the first, there is a lot of tension and distrust between Mal and Simon. This is due mainly to their similarities: both would do anything to protect their respective families, and both fears that the other is a threat to that. To Mal, his crew is his family, and he tolerates and accepts Simon and River as long as they do not threaten their wellbeing. Simon is likewise devoted to River, and often feels that Mal is flippant with her, and unconcerned with her safety. These two goals often conflict, despite Simon technically being part of Mal's crew.

River Tam was the teenage sister of Dr. Simon Tam, both of whom took refuge aboard Malcolm Reynolds' Firefly-class transport ship known as Serenity. She is considered a child prodigy, intelligent beyond her years and athletically gifted. After intense experimentation by Dr. Mathias on behalf of the Parliament – the Alliance ruling body – River was partially transformed into a mentally unstable psychic weapon intended for secret governmental use. She was rescued at great cost by her brother Simon but tracked relentlessly by several agents of the Alliance, primarily Lawrence Dobson, two blue-gloved men, McGinnis, the bounty hunter Jubal Early, and finally the Operative. Almost all of her time on the run was spent with the crew of the Serenity, who became her extended family.

During River's early childhood, she grew up alongside her brother, Simon, part of the wealthy Tam family on the "Core" planet of Osiris. It is remarked often that she was extremely gifted intellectually from a very young age (she is noted as having “corrected Simon's spelling since she was three”), and also very graceful. She has been portrayed and described consistently as having always had both a strong thirst for knowledge and a love for and intuitive grasp of dance. By the time she was 14 years old, she had grown “bored” with her studies and was already in the graduate program for physics.

It was at this point that she was sent to a government learning facility known only as "The Academy". While her parents and Simon believed the Academy was a private school meant to nurture the gifts of the most academically talented children in the Alliance, it was in fact a cover for a government experiment in creating the perfect assassin. While in the hands of the Alliance doctors and scientists, River was secretly and extensively experimented on, including surgery that stripped her amygdala.

After learning about River's abuse at the Academy, Simon is unable to help her for two years. However, Simon is eventually contacted by a group of men from an underground movement. They explain to him that the Alliance has been "playing with her brain". If funded, the men agreed to sneak River out in cryo. River would then be taken to Persephone, a planet slightly outside the Core, from where Simon could take her wherever he wished.

Simon spends a large amount of money funding the men. As part of the plan, he infiltrates the Academy disguised as a uniformed official of the Alliance government and asks questions of Dr. Mathias about River's treatment. Simon activates a hidden stun grenade and releases River. They then run to the window of an elevator shaft, break through, and the men's ship overhead releases a raft that they use to ride up to safety. This was all caught on the security cameras of the Academy.From there, they headed for Persephone.

When the Alliance learned of River's rescue, they promptly froze all of Simon's monetary accounts, leaving him with only that which he had with him at the time, and put out a warrant for the arrest of both Simon and River, labeling them as fugitives.

Shepherd Derrial Book (born Henry Evans) was a passenger aboard Serenity, and a friend and spiritual teacher to its crew. Before his time aboard the ship, he led a life marked by violence and conflict, both inside and out, which remained a secret from the crew.

To the crew of Serenity, Derrial Book's past was a mystery. He indicated early on that he was a shepherd who had been living in the Southdown Abbey and that he never married. In truth, "Derrial" was not even the shepherd's real name, but rather the name of a man he had killed.

Book, whose birth name was Henry Evans, lived as a young boy in dread of his highly abusive father. He would listen to music to take himself to a peaceful place in his mind, only to be beaten. Ten years after leaving home, he had established himself as a successful thief adept at avoiding law enforcement, but this was not what he had envisioned for himself. He was then recruited by the Independence Movement after a representative became impressed at Evans' excellent combat potential. In four years he honed his fighting skills, easily defeating heavily-armed federal agents single-handedly. Evans was not known among his Independence peers to attend their meetings, but he showed up for one and there he volunteered to take part in a highly-sensitive mole operation. Since the Independence organizers had learned that the Alliance was creating warships, they plotted to plant a long-term mole to rise through the ranks of the Alliance and subvert them at every turn. Henry's left eye was extracted and replaced with a biorobotic camera and transmitter, which would provide excellent surveillance. To join the Alliance, he needed a new identity. So he lured an unsuspecting young man named Derrial Book into an alley, murdered him with a garrote, and took on this name permanently.

Mr. Universe

Mr. Universe was a reclusive techno-geek. He lived (apparently) alone on a moon with his love-bot "wife", Lenore. He had a great affinity for data and was capable of intercepting nearly any transmission or recording in the system. He was seen stepping on a cloth-wrapped glass (as well as wearing a yarmulke) in a video clip of his wedding, indicating that he may be Jewish.

He was killed by the Operative as part of a trap the Operative set to capture the crew, but had set plans in motion for Malcolm Reynolds to broadcast a report from a Union of Allied Planets scientist that revealed the origins of the Reavers.

Mathias

Dr. Mathias was the doctor who headed the research project which resulted in River Tam's psychosis and increased abilities. He was very proud of his achievements and the importance it brought to him. Mathias was present when Simon Tam managed to free River from the medical center. Following questioning by the Operative about River's escape, the Operative killed Mathias for his failure, talking to him all the while.

The Operative was an agent of the Union of Allied Planets government. Similar to a black ops agent, the Operative's work was not acknowledged by the government. He didn't officially exist; he gave up his name upon becoming an operative, and he did not hold an official rank in the Alliance.

His status as an operative could get him access to most (possibly all) Alliance facilities as well as respect from those who knew what an operative was. He had been highly trained in close armed and unarmed combat. Until he had his faith broken, he was unswervingly devoted to his cause. After Hands of Blue failed to secure River Tam, the Operative was called in to hunt her down. He first visited the facility where River was held before her brother Simon broke her out, reviewing a holographic recording of the escape. When Dr. Mathias found him and asked to see his security clearance, the Operative showed his position. Though the Operative understood that Simon was acting out of love for his sister, he was more concerned about keeping whatever secrets River gleaned from the minds of key members of Alliance Parliament during her training, which Mathias mentioned to Simon on record. For this, the Operative killed Mathias' bodyguards with his sword before paralyzing Mathias with a nerve jab, letting Mathias fall on the Operative's upturned sword .

To locate River, the Operative began broadcasting subliminal messages in advertisements all over the Alliance. Eventually, he found her on Beaumonde, having gone on a rampage through a bar, the Maidenhead, before her brother subdued her with a Russian safe word. Noticing on camera another man picking River up, the Operative ran a search and identified the man as Malcolm Reynolds, a former Browncoat and captain of Serenity. Tracing leads to any of Mal's associates, the Operative located Inara Serra and used her to lure Mal into a trap. He tried convincing Mal that River would "rain destruction upon [him and his] ship" and would be better off returned to the Alliance. His threats to fire on Serenity via its pulse beacon proved futile, as Mal had already removed it and continued to insult the Operative, who proved resistant to his taunts. Mal then shot the Operative in the chest, unaware that he was wearing body armor, enabling him to gain the element of surprise when Mal's back was turned. Once the Operative had Mal beaten, he was thrown back by a flash bomb prepared by Inara, enabling the two to escape. Once he regained his senses, he called his ship in orbit to track Serenity via NAVSAT, but his quarry had deployed several decoys.

The Operative soon ordered simultaneous attacks on any ports that once harbored Serenity, including Haven, to give his quarry no place to hide. He then contacted Mal, promising more of the same until River was handed over. In response, Mal had his ship modified to look like a Reaver vessel to bypass Reaver lines blockading the planet Miranda, where they attempted to locate whatever secret the Alliance was hiding. The Operative suspected that Mal would try and broadcast this secret to the Verse and tracked down Mr. Universe, the reclusive hacker who had a transmitter capable of overriding all Cortex channels. Once he forced Mr. Universe into luring Serenity into a trap, the Operative killed him, destroyed his transmitter and called in an entire fleet to intercept Serenity.

The Operative failed to anticipate Serenity luring an entire Reaver fleet to Mr. Universe's planet, forcing him to order his fleet to focus fire on the Reavers. During the battle, a large Reaver ship rammed into the Operative's, splitting it in half. Grabbing a stun gun from a fallen soldier, the Operative took an escape pod and followed Serenity to the surface. Making his way back into Mr. Universe's complex, the Operative came across Mr. Universe's love-bot, Lenore, who had left a message for Mal, directing him to a secondary transmitter he missed. Confronting Mal, who smugly noted that he had finally made him angry, the Operative reminded him that he was responsible the deaths of innocent people in bringing the Reavers. Mal stated that he didn't know how true that was and that he knew the secret the Alliance was intent on keeping hidden and planned to expose it. He then outdrew the Operative, shooting the gun out of his hand and forcing him to take cover. The Operative chased Mal to the transmitter before fighting him, only to be defeated when his traditional nerve cluster strike failed due to an old war wound's having caused the cluster to be moved. Mal punched the Operative's throat, leaving him gasping for air, before dislocating his arms. Instead of finishing him off, Mal decided to show the Operative his "world without sin" and forced him to watch a report by another Alliance officer, Caron, revealing that it was the Alliance itself that had been responsible for accidentally creating the Reavers during their attempt to calm the population of Miranda. His faith in the Union of Allied Planets shattered, the Operative ordered his troops, poised to kill River, to stand down.

The Operative soon arranged for repairs to Serenity on Persephone and called off the search for the Tams. He then faced Mal one last time, telling him that exposing the truth about Miranda might have weakened the Alliance regime, but he couldn't guarantee that they wouldn't come after him. As for himself, the Operative confessed that he would leave the Alliance. Mal threatened to kill the Operative if he saw him again, which the Operative assured him would not happen.