Civil War Captain America: After an untrained hero's mistake cost innocent lives, the U.S. government required that all super-powered beings register their names and abilities. While many heroes felt that the move was the right one, Captain America thought the loss of liberty was too great, and went underground.

Arnim Zola: Arnim Zola was a brilliant scientist in the field of artificial intelligence and brain cloning, but he chose to use his knowledge to create super-soldiers for Captain America to fight, as well as a robotic body for himself. Now, with his personality backed up on hard drives, Zola is virtually immortal.