Mechaturtle

Mechaturtle is a villain in the Teenage Mutant Ninja Turtles NES game. He is the boss of level 3.

Appearance
Mechaturtle's initial appearance is that of a blue-green, purple, or blue skinned Teenage Mutant Ninja Turtle with a tan or green headband and joint pads. Upon this form's defeat, it reveals its true appearance; a vaguely turtle-esque automaton.

Plot
The turtles return to their lair. The place is trashed when they arrive. Suddenly, Shredder greets them with a message: Splinter has been kidnapped and they must rescue him. They search Wall Street in their custom van. The van reaches a road block and the turtles are forced to walk. They encounter many obstacles such as foot soldiers and robots. Eventually, they find Splinter on top of a tall building located at the end of Wall Street. After ascending the stairs and defeating more obstacles, the turtles find their master tied to a post. He is being guarded by Mechaturtle; a robotic turtle that almost resembles the Ninja Turtles. It starts to fight them. Both sides are almost equally matched except the turtles are stronger. Moments later, Mechaturtle sheds it's skin, revealing its full identity as a robot. The robot uses heat seeking missiles and a gun to annihilate its foes. It fails after enduring many attacks. Mechaturtle explodes and the turtles rescue Splinter.

Confusion
Many fans mistake Mechaturtle as Slash who is another villain in the TMNT franchise. These characters are entirely separate. Slash's body is green whereas Mechaturtle's body is dark. Also, Slash isn't a robot.