Bucky Barnes, also known as the Winter Soldier, is a significant character in the Marvel Cinematic Universe. Once a close friend of Steve Rogers, he was presumed dead during World War II but was later found by Hydra and brainwashed into becoming an assassin with a cybernetic arm. In 'Avengers: Infinity War,' he is a key ally, fighting alongside the Wakandans and the Avengers against Thanos. His character arc revolves around redemption and reclaiming his identity after years of being a controlled weapon.