Boomer, officially known as CS-2207, was an ARF trooper sergeant of the 501st Legion during the Clone Wars. He was placed under the command of Anakin Skywalker and Captain Rex, who he became close friends with. Boomer and Rex were scouting the Ryloth wastelands for enemy droids until the bounty hunter Cad Bane captured them both. When the two were captives, they were forced to work with Bane on defeating droids trying to take a crate Bane stole. Bane told Boomer and Rex if they did not cooperate, they would be killed by the detonators in their binders. Later, when Anakin and Ahsoka arrived, Boomer and Rex guarded the Jedi by facing several droids.
Boomer wore ARF trooper armor with several blue markings throughout in striped patterns, a holster for a DC-17 Hand Blaster, and used a DC-15A Blaster Rifle as his weapon of choice. Boomer's visor was painted over entirely blue and a faded stripe ran down the midsection of his helmet.
- Republic Heroes (First appearance)