Titanus is the leader of H.A.V.O.C. and thus a strong enemy of the Turtles.
He's a large mutant from the future who created a bunch of mutants to overpower the humans and destroy the city. He appeared in Season Eight of the 1987 TV series, in three episodes: "Cry H.A.V.O.C.!", "H.A.V.O.C. in the Streets!", and "Enter: Krakus". He's not a good fighter and is easily defeated by the Turtles every time. In the end Donatello teleported him to the Dinosaur Age where he's last seen being chased by a large dinosaur and saying he'll get revenge on the Turtles if it's the last thing he does.
He is voiced by Rodger Bumpass and Ronald Feinberg.