Thor

Thor's father Odin decided his son needed to be taught humility and consequently placed Thor (without memories of godhood) into the body and memories of an existing, partially disabled human medical student, Donald Blake.  After becoming a doctor and on vacation in Norway, Blake witnessed the arrival of an alien scouting party. Blake fled into a cave after they heard him and began to pursue him. After discovering Thor's disguised hammer Mjolnir, and striking it against a rock, he transformed into the thunder god.