James Buchanan "Bucky" Barnes

First appearing in Captain America # 1 (1941), Buck was a scrappy kid born in Shelbyville Indiana in 1925, and became an orphan after his father was killed in training before America's entry into WWII at Camp Lehigh, Virginia. There he became the unofficial mascot of the camp and made friends with Private Steve Rogers, who Bucky believed to be a dull-witted guy, unaware that Steve was secretly Captain America. Upon discovery of Steve's secret, Bucky became Cap's partner. Together they fought many enemies of the Allied Powers during WWII, including the infamous Red Skull. On their last mission together, against Baron Heinrich Zemo, they hopped aboard a drone plane that was laden with explosives. Steve was knocked off the plane, and Bucky was blasted clear of it, losing an arm in the process. A passing Soviet submarine picked him up, and due to the explosion he was stricken with amnesia. He was taken to Moscow and scientists attached a bionic robotic arm, upgrading the arm every time the technology improved. He was put through a rigorous training course and becomes the Winter Soldier, their top covert assassin. It was not until the 21st century, when Bucky was sent by the former Soviet General Aleksander Lukin to kill the Red Skull that he and Cap meet. Afterwards he goes on to kill hundreds of people in Philadelphia, kidnap Sharon Carter and charges the Cosmic Cube, which Lukin sent him to collect. When he and Steve struggle for the Cosmic Cube, Steve gains control and tells the Soldier to "remember who you are". Upon being hit with the flood of memories and the overwhelming guilt for what he did over the years, Bucky flees. Over time, he regained the trust of his friends, and upon Steve's supposed death, he became the new Captain America, at the request of Steve. Upon Steve's return, he is willing to give back the mantle to his former mentor, but Steve declines, telling Bucky to continue on. Bucky joins the reformed Avengers after the events of 'Siege' and is soon put on trial for his crimes as the Winter Soldier. Bucky will be played in the upcoming Captain America movie by Sebastian Stan.