There's Karate Kid of the Legion of Superheroes, who's clearly stated to technically have no superpowers and is just really, really good at martial arts. Karate Kid, whose feats are also clearly to the point where it might as well be a superpower (e.g. breaking glacier ranges, shattering energy force-fields, etc.)
Meanwhile, at Marvel, Captain America, who's supposed to unequivocally be the greatest fighter on Earth, can pull nary a superhuman feat.