Winter Soldier

Captain America's sidekick during World War II, James "Bucky" Barnes was thought to have been killed in action. In truth, he had been recovered by enemy forces and rebuilt into their ultimate assassin. But the Winter Soldier eventually broke his conditioning to become a hero once more.

Captured during an operation to sabotage Erebus Base, the Winter Soldier was subjected to horrific experiments at the hands of Hydra scientists. He was rescued by Hawkeye and a version of Captain America from the year 2099, who gifted an upgraded arm to his former partner.