Sauron is a humanoid pterosaur supervillain from Marvel comics. He is an alter ego of the physician, Karl Lykos. He possesses the power of hypnosis. He is also an energy vampire who drains energy from super powered beings, but turns into his mutated form as a side effect. He's currently a resident of the Savage Land, home of the superhero, Ka-Zar. He is also a common enemy of the X-Men.
While the Majestic Guardians were exploring the island, they were chased by the Ape-Men and Katara became separated from the group. Sauron used this opportunity to capture the heores and drain their energy with the help of his lackey, Stegron. But his plan is foiled thanks to the team-up between Katara, Ka-Zar and Zabu.
He is not to be mistaken for J.R.R. Tolkien's character from "Lord of the Rings" who shares the same name.