TJ-55 is a T-series Tactical Droid serving as a commander in the Separatist Droid Army and an antagonist in the Star Wars: the Clone Wars episode "The Hidden Enemy".
TJ-55 led a droid army on Christophsis were he and another tactical droid were to help General Whorm Loathsom. He was first seen in an Armored Assault Tank where he shot down towers in his way and then followed Republic troops on the south tower's roof. He managed to shoot and kill one of the Clones, and led his droids in attacking the rest to prevent their escape but failed in doing so and the droid had his head ripped off by a Clone, causing him to walk in random directions because he couldn't see without his head. His head was used by the Republic to get some information about how the droids knew they were there, and discovered a Republic traitor is working with the Separatists which later on turned out to be Clone Sergeant Slick who was later arrested.