The T-500 Endo is a villain in the Terminator Salvation: Trial by Fire novel. It is mentioned in the novel. Its physical appearance is in The Terminator: Dawn of Fate.
The T-500 Endo is one of the early Humanoid Hunter units. It is a predecessor to T-600 Terminator model. Skynet deploys the the T-500 on the battlefield. The T-600 also serves as infiltrating territories.
The T-500 is supported by a chassis that is durable in battles. The unit also utilizes weapons that short lasers. Like newer Terminator models, some T-500's are covered entirely in human skin. The actions of the T-500 are synced to it's AI program.