Titannus was a Skrull criminal born without the shape-shifting abilities of his alien race. He participated in the early Super-Skrull program thus granting him superhuman strength and advanced healing abilities. He eventually escaped the Super-Skrull program and rampaged across his home planet. He eventually allied himself with the Trellion leader Toth, who somehow managed to brainwash him into bringing the Avengers and several other heroes of reality-5012 to the planet Trellion. Captain America and Wasp sacrificed their lives while battling Titannus and the Trellions in what came to be known as the "Titannus War."