Challengers of the Unknown Week: Trifecta of Terror
The other two members of Earth-One's League of Challenger-Haters, arch-enemies of the Challengers of the Unknown, were menacing in and of themselves. And yet, whether by themselves or with their allies, they proved failures.
Volcano Man was the creation of an evil scientist, or was he? Regardless, he multiplied into other volcano men and proved a hot-headed foe on more than one occasion, eventually realizing he had to join follow felons captured and held within Challenger Mountain. His counterpart was the equally mysterious Nebula Man who faced the Seven Soldiers of Victory. He was replicated into a gigantic hand that once threatened Earth-Two.
A future teammate of Volcano Man was King Kra, himself from a planet of robots. Dominating the organic life forms of his world, he found his reign squelched by the visiting Challengers. So he sought out kindred spirits... losers all..in the Challenger-Haters!
There was a similar being known as King Ironsides on Earth-Two, yet within the creature was the lookalike brother of Wonder Woman's old foe Doctor Psycho, a man named Wilhelm Psycho who was actually a geologist and the counterpart of Kra. An ally of Kira's and fellow Leaguer was Multi-Man aka Duncan Pramble who himself faced Wonder Woman as had his counterpart Kang. The Amazing Amazon beat this King and his mechanical minions quite easily, and he never returned, unlike his more persistent sibling.
And it was his Iron Giants who were the counterparts to the artificial automatons known as the Volcano Men, as both were tied to volcanos with Ironside's minions seeking diamond on. The other giant member of the Challenger Haters, Multi-Woman, was paralleled by Miss America who left her native Earth-Two for Earth-X with her fellow Freedoms Fighters, never to return.