Origin

Leoninus is the leader of the evil Changelings. The original Changelings are created by Woodgod and they capture General Thunderbolt Ross, Betty Ross, Fred Sloan and Rick Jones. Woodgod places them in their custody after one of their fellow Changelings named Centauron is wounded by an ill Thunderbolt Ross. Leoninus secretly poisons Centauron and he dies. Leoninus places the blame on the humans and feel they should be executed for harming a Changeling. Leoninus and his evil Changelings challenge Woodgod's leadership and accuses him of favoring the humans.

An original Changeling named Siren discovers that Leoninus poisoned Centauron with cyanide and seeks the Hulk and Doc Samson for help. A huge brawl takes place between the original Changelings and the evil Changelings. Leoninus is defeated by Woodgod after receiving a running headbutt from his creator. The evil Changelings are defeated and the current whereabouts of Leoninus are unknown.  

Creation

Leoninus was created by Bill Mantlo and Sal Buscema in 1980 and first appeared in The Incredible Hulk # 252. 

Powers & Abilities

Leoninus is an animal man with lion attributes. He has razor sharp claws and a degree of superhuman strength. Leoninus also possesses enough intelligence to create his own group of Changelings after reading the notes from Woodgod's laboratory.