Berserker (Marvel Comics)

Berserker is a fictional character appearing in American comic books published by Marvel Comics. The character first appeared in The Avengers #207 (1981).

Fictional character biography
The Berserker was an ancient man who became immortal when he was empowered by the Cave of Glowing Walls, and fought the Avengers when he was freed in modern times, and was banished to the Shadow Realm.