Ulthro was a super-villain that approached Superboy and the Legion Of Super-Heroes to defeat them. He had a lead-based mask that prohibited Superboy from seeing who he really was. Urthlo also carried an item that cancelled the super powers of the Legion as well as Kryptonite laser vision to disrupt Superboy's power. The Legion of Super-Heroes was able to free Mon-El from the Phantom Zone temporarily to beat Urthlo, revealing that he was a robot that looked like an aged Lex Luthor. Lex Luthor created Ulthro and sent him into the future to defeat the superhero team, but failed.