Namor the Sub-Mariner was Marvel's first (anti) hero created. Namor wished to protect his kingdom from any attack, and that included all of mankind. Namor once fought the Avengers, who won him over to their side for a while, but Namor soon proved to be a neutral figure in the Marvel world. However, during a conflict between the Avengers and X-Men, Namor attacked Wakanda and went fully over to the Friends. Namor was granted a Fear Aura and some ability to corrupt victims of his. While the High Council are still working to save 616 Black Cat, they consider Namor a lost cause. He was finally slain by the Squadron Supreme following the Secret Wars event, which lead to his soul fracturing into two pieces, one to serve the Friends as a warrior and the other half trapped in a deathless limbo until Marvel decides for him to come back.
Even before he gained his Fear Aura, he could fly and mimic aquatic animals. These powers were only enhanced by the Friends.
When he isn't terrorizing seafarers, he's guarding the base of the Genetic Experiment Division.