Turtle Man came from wanting a weapon thats basically a Koopa Shell from the Mario games, and working backwards to make a robot that would provide that. He's naturally based on Bowser, but a lot of his design is loosely inspired by the couple of other turtles that show up in the Mega Man games, like Gamerizer from MM7. He's also kind of evil - his job is to "protect wildlife" from things like garbage and pollution, but takes it to it's natural extreme of "wildlife would be protected best if there was no pollution, and the best way to get rid of pollution is to get rid of humans." He was friendlier looking but self-modified to appear threatening. Despite that, Turtle man is actually pretty gentle with animals.