Superheroes took all forms and all types of superpowers throughout the Golden Age of the 1930s-1950s. By the time the Silver Age of the 1960s rolled around, fresh material was a bit scarce. But Marvel's king of fresh ideas, Stan Lee, decided to explore a whole new world...Norse Mythology. He cast his gaze about for an appropriate protagonist, and discovered fertile ground in the legends of the Thunder God Thor. According to Wikipedia:

"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.".

"While on holiday in Norway, Dr. 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."