Winter Soldier is James "Bucky" Barnes, who after being seriously injured in World War II, was found by Russians who transformed him through freezing and mental manipulations into the Winter Soldier, a cold assassin responsible for important political assassinations that only managed to recover his memories thanks to Captain America.
In the Marvel Cinematic Universe he is portrayed by the actor Sebastian Stan. Bucky Barnes has an implanted bionic arm that gives him strength and superhuman reflexes. In Avengers: Infinity War he vanishes after the Thanos snap.
Now, the Winter Soldier is back in Art Scale 1:10 form for Avengers: Endgame with a fully detailed base and an updated likeness of Sebastian Stan.