Fans of Marvel and DC will argue until they're blue in the face about who is the most powerful out of Thor and Superman, but the pair have actually fought to a definitive outcome in a crossover comic. 2003's JLA/Avengers miniseries saw the pair having a few little scuffles. before a final fight that had them exchanging punches until Superman got the better of the Asgardian with apparently superior physical strength and his heat vision. Superman stated that Thor may have been the toughest single opponent he had ever gone up against, which was something of a silver lining for fans of Thor. However, given that crossovers like this aren't canon, those fans don't really have anything to worry about anyway, but the fact is Marvel's hero got beaten up by DC's icon.
