Kal Skirata, born Falin Mattran—sometimes called Kal'buir (Mando'a for "Papa Kal") by the clone commandos that he trained—was a Human male Mandalorian instructor who trained clone commandos in the Grand Army of the Republic during the time of the Separatist Crisis. After being orphaned, he was adopted by Munin Skirata. As Skirata grew up, he became the husband of Ilippi Jiro and the biological father of Tor, Ijaat, and Ruusaan Skirata. He would also become the adopted buir of Omega Squad and the Null-class Advanced Recon Commandos, RC-1136 of Omega Squad, and Jedi Knight Etain Tur-Mukan, and ex-Jedi Knight Bardan Jusik. He was also the adopted grandfather of Venku Skirata.

RC-1309 was a clone of Mandalorian bounty hunter Jango Fett, grown in secret on the planet Kamino as part of the Grand Army of the Republic. Born in the year 32 BBY, he was one of the one hundred and four clone commandos trained by Mandalorian Cuy'val Dar training sergeant Kal Skirata, RC-1309 adopted the name "Niner" for himself, based upon the last digit of his numerical designation. He would serve as the squad sergeant for his first squad, and came to care deeply for his brother clones.

During his training, Atin gained several scars from battle. These were partly due to the regular training, but also for another reason: Walon Vau. Vau was a ruthless training sergeant, making his soldiers fight each other, or fight him. Vau made Atin choose after he lost his first squad, who were killed in training while trying to rescue him. Atin did not want to fight his brother clones, and instead opted to fight Vau. Vau nearly killed Atin with a Mandalorian saber. Vau's training was brutal, and Kal Skirata saw him as a sadist. He joined a second squad after being the sole survivor of his first squad.

Darman was a Republic Commando assigned to Theta Squad and trained by Sergeant Kal Skirata. During his first mission on Geonosis, Darman lost contact with his squad mates and called for each man personally over the comm; none replied. He waited until the last LAAT/i left to see if his squad mates would return, but was forced to acknowledge that all other members of Theta Squad had been killed. Darman was re-assigned to Omega Squad along with Niner RC-1309, Fi RC-8015, and Atin RC-3222. He was considered their demolitions expert. He served alongside his squad members until the end of the Clone Wars, when half the squad deserted to Mandalore.

Fi began his life on Kamino, like every other clone in the Grand Army of the Republic, and spent his early years training under Kal Skirata. His first deployment was to Geonosis, during the first battle of the Clone Wars. Due to Jedi incompetence, all three of Fi's squadmates were killed during the battle, which led to his being reassigned to Omega Squad with RC-1309, RC-1136, and RC-3222, three other commandos who were also the sole surviving members of their squads. Fi was the first of the newly formed Omega Squad to report for duty, although he and his new sergeant, Niner, would have a tense first meeting. Fi would go on to become an integral and valued part of Omega Squad. His sense of humor and generally sunny outlook would help to ease tensions in the squad through difficult times, a trait which greatly helped the squad in their first mission together.