Bucky Barnes (Marvel Cinematic Universe)

James Buchanan "Bucky" Barnes is a fictional character portrayed by Sebastian Stan in the Marvel Cinematic Universe (MCU) media franchise—based on the Marvel Comics character of the same name. Barnes is childhood best friends with Steve Rogers and serves alongside him in the Howling Commandos during World War II. Barnes is seemingly killed in action, but is actually captured by elements of Hydra within the Soviet Union.

Source: Wikipedia — Bucky Barnes (Marvel Cinematic Universe) (CC BY-SA 4.0)