Super-Villain Team-Up (1975) #2

Sub-Mariner

Prince Namor is the half-human/half-Atlantean ruler of Atlantis.

Tiger Shark

A champion Olympic swimmer, Todd Arliss earned nearly half million dollars in advances for public exhibitions, but his dreams came crashing down around him when he injured his back and legs while rescuing a man who had fallen overboard from a private craft, sending Arliss into the arms of Dr. Lemuel Dorcas, who used his "morphotron," which could imprint the genetic pattern of an animal onto a human, turning Arliss into a superhuman, amphibious creature.