A Golden snub-nosed monkey, who originally lived at a Buddhist temple where she was worshiped as a goddess. She continues to act as a goddess with the rest of the crew even, on occasion, addressing herself in the Royal "we". This leads to considerable tension at first, though over time she warms to the others and vice versa. Skilled in martial arts and knowledgeable in Buddhist wisdom, she is Captain Simian's first officer. There are occasional hints of a romantic attraction between her and the Captain, though this was never developed.

A wisecracking little spider monkey, originally the property of an organ grinder from New York City. A pickpocket, grifter, and all-around thief, he often tries to take advantage of Gor by trying to get him to do his work and trying numerous get-rich-quick schemes which get him into trouble with the Captain. Despite these flaws, Spydor is loyal to the mission, and will never betray his friends or the universe for money. He is especially close to Gor, and will not let anyone else take advantage of him. Spydor is in charge of communications.

A gorilla originally from Rwanda as a dominant male and the crew's muscle. During the evolution process he accidentally wrecked the intelligence-enhancing machine before its completion. This left Gor rather naive and childlike. Possessing extraordinary strength, Gor is naturally quite peaceful and does not wish to do anyone harm. But when his friends are in danger he can go into a berserk rage. In an early episode Apax kidnapped Gor to make him a prize fighter, but since Gor's peaceful nature did not permit him to fight needlessly, Apax experimented on him, turning him into a mindless, raging gigantic King Kong-like gorilla named Gormongous. Dr. Splitz was unable to reverse the effect of Apax's isotope, meaning that Gor turns into Gormongous whenever he gets angry, in a manner similar to that of the Incredible Hulk.

A former zoo orangutan with a dual personality that alternates between an effete academic ("Dr. Splitz") and a rustic yokel ("Splitzy"). The doctor excels at scientific theory and somewhat cowardly, while Splitzy is a mechanic and engineer eager to jump into a fight. The two personalities are aware of each other and bicker constantly, but often rely on each other to make up for their individual shortcomings.

A small ball-shaped robot, given to Charles by The " " to help him on his mission. Its role was to provide the monkeys with the additional knowledge they required for their journey. Already quite cynical and unpleasant, it was accidentally damaged by Gor and subsequently went quite insane, floating around sputtering nonsense that only occasionally makes sense. This leads Captain Simian to often say, "Gotta get that thing fixed." Because it is so technologically advanced Splitzy was unable to repair it despite trying.

Holographic baboons created by Dr. Splitz to test out the atmosphere of unknown planets. They are voiced by Jeff Bennett, with a number of celebrity impressions (such as Beavis and Butt-head, Jerry Lewis, Woody Allen and The Three Stooges). They are a parody of the redshirts from the original Star Trek series, and almost always get destroyed.

Lord Nebula- Nebula is a half-humanoid, half-black hole who hoped to become a complete black hole, swallow the universe in a “Big Crunch,” then remake it in his own image. The gaseous nature of nebulae is employed as a running gag, as Nebula seems to constantly suffer from some cosmic analogue of gastro-intestinal distress. In the series finale he is trapped in an orb and Rhesus 2 takes over.

An enforcer of Lord Nebula. Originally a rhesus monkey sent into space, Nebula made him intelligent and turned him partially into a robot. His brain is detachable and frequently changes from one to another in order to get different ideas. For example, Brain 1 might give him a more devious plan than Brain 2 or vice versa.

An alien with green skin and snakes in place of hair. Apax forces other alien creatures to fight in an arena. At one point, he injects an isotope into Gor, causing him to turn into a monster whenever he gets angry. He often says "Only in Andromeda!"

An owner of a club on Maltese 1, who simply planned to steal the Primate Avenger, but had to go under the identity of Gorr when someone else replaced him to steal the Orbitron and sell it to Nebula, as Orbitron keeps repeating "0-1-0-0-1-0-0-1-0-1... oh, and 0-1.", which was the formula for the GLOP (Gravi-Luminous Orbifolding Positrons), which had the component needed by Nebula, the Anti-Force.

A swashbuckling space adventurer who meets the crew in a bar in the episode "Monkey Puzzle Man". Initially appearing as a blue-skinned humanoid, Largo gradually turns into a monkey-like creature as he hangs out with the crew, since he can duplicate another's most distinctive characteristic (martial arts skills from Shao Lin, who he flirts with, for example) after making physical contact. Everyone likes him except Simian (who insists there's something weird about Largo) and Gor (who resents Spydor spending more time with Largo then him), but are dismissed as jealous. Largo invites the crew back to his 'home', but it turns out to actually belong to Rhesus 2, whom Largo is working for. After making contact with Captain Simian, however, Largo realizes the error of his ways and helps the monkeys escape, apparently sacrificing himself to give them time to get away. However, it turns out at the end he managed to escape and leaves aboard a separate ship.

A being of infinite powers, who appears to be a mandrill able to float in space and midair, go through walls, be invulnerable to attacks, and be able to connect with others' minds. He speaks in ominous and cryptical phrases and seems to know everyone in the crew better than they know themselves. The last image of the series is the revelation of him being Captain Simian from the future.

Lilith identifies herself as the caretaker of the planet, After an alien race recently visited, got rid of all poverty and pollution, and made all species intelligent. The others all left to explore space, leaving her behind as the chosen caretaker.

A powerful being calling himself the Glyph offers Simian the chance of destroying Nebula. The plan is to lure Rhesus 2 into a trap and get him to lead them ..

Keeper of the Great Ear. This ear is the one of the Sleeping Giant, whom Grxilpix tells the monkeys is dreaming about the whole universe. Anything that someone asks for to the ear appears. Rhesus attacks Captain Simian and his crew next to the ear, and in their fight, they awake the giant, causing the universe to disappear. Dr. Splitz then plays a lullaby on a handheld device, causing the giant to return to his slumber and the universe to be restored.

Vog is a 2-dimensional alien. When Rhesus 2 steals gravitons from a cosmic storm, Vog's world rips open, so he follows Charles to his universe and asks his help to put the gravitons back before the cosmic storm ends to seal the rip and save his universe.

A computer that captures the Monkeys and learns from them to eventually evolve into a living being.

An advanced alien race that is so advanced, the name of their species cannot be spoken or written, only thought. They intercepted Captain Simian while he was still a wild chimpanzee. Believed to be a human broken free of his evolutionary bonds, they gave Simian "The Gift", which is advanced intelligence and the power of speech. They assigned Simian to stop Nebula before he gets the anti-force and completes his dark goal which is to destroy the universe and create a new one within himself. During the series, The " " retreated to the 10th dimension until part one of the series finale, where they warn Simian that Nebula is getting very close to his goal.