In the 1980s, superhero comics were in the process of reinventing themselves for a more sophisticated audience, and one of the creators who took advantage of that was writer/artist Walt Simonson when he took the reins at Marvel Comics’ Thor.
Chris Clarememont and John Byrne had made their mark on The Uncanny X-Men; Frank Miller and Klaus Janson had overhauled Daredevil into something epic. (Byrne and Miller, of course, later revolutionized Superman and Batman, respectively.) But Simonson, who had worked on The Mighty Thor in the late 1970s, already had mythic material to start with, and when he returned to the title he built it into a world-shattering story.