Let's not forget many antiheroes are essentially reluctant heroes. Godzilla, a villain, became an antihero since Ghidorah the Three-Headed Monster (Toho; 1964), where he and Rodan were convinced by Mothra to fight against King Ghidorah, a greater evil, to protect the Earth and all humankind. Of course, Godzilla became a neutral good guy, protecting his home territory that was the Earth, but he was still destructive, and still didn't exactly care for humans. At least until Godzilla Vs. Gigan (Toho; 1972)!
Even Edward Scissorhands has been called, by Tim Burton, "The ultimate antihero. He can't touch."