Bucky Barnes

Serg. James Buchanan "Bucky" Barnes is the believed-to be deceased best friend of Captain America. During his time in World War II, he was a member of the Invaders and helped lead the Howling Commando's. He was saved from death after being recovered by Russian scientists in a snowy forest and he was brainwashed and trained to become the Winter Soldier. He's been a KGB agent, a known HYDRA asset, and currently is an international mercenary.