Possibly my favorite TMNT villain, Armaggon the Future Shark! I knew him from his appearances in the Archie version of Turtles, "Teenage Mutant Ninja Turtles Adventures", but many turtle fans know him better from the SNES version of TMNT: Tournament Fighters. This drawing is largely based on his appearance there, and I swiped the color palette directly from it.
Game Grumps fans might know him better as "Arm Gone". XD
Armaggon was created by Peter Laird and Stephen Murphy and now belongs to Nickelodeon, if I'm not mistaken.