Titano and Marcopidae Gigantis, mutants from among their kind possessing tremendous power and bestial instincts guiding them.
Earth-One's Superman had to face the former chimp Toto, now transformed during a flight in a space capsule by Kryptonite radiation and growing large. Emitting green Kryptonite eye beams, the Man of Steel depended on his girlfriend Lois Lane and best buddy Jimmy Olsen to defeat him. Eventually, he was sent to an alien world of giant beasts.
Earth-Two's Green Lantern and Doctor Mid-Nite, alongside their best buddy Edmund Blake, encountered the immense Marcopidae Gigantis, in a secluded Australian valley of such creatures. Lantern himself used green beams in the form of boxing gloves to try subduing the beast, until Mid-Nite intervened with some creative ingenuity to cause the creature to flee, never to reappear.