Created by Stan Lee, Larry Lieber and Jack Kirby, Thor made his first appearance in the Marvel comics in August 1962 
in the issue of Journey into Mystery and was based on the Viking God of thunder and protector of the Earth. 

In a few years his popularity rose to the point that Marvel had to create a comic-book series called The Mighty Thor.

According to Norse mythology (also referred to in the Marvel Comics), Thor and the other Gods of Asgard 
gained their immortality from eating the magical Golden Apples of Idunn, which grow in Asgard and can only be picked 
by the goddess Idunn. He has to periodically return to Asgard in order to renew his immortality.