Best know for the 80's cartoon show and series of 90's live action films, they started out in a much darker origin than their kid friendly animation lets on.
The Turtles were created by Kevin Eastman & Peter Laird in 1984 and first appeared in a comic book published by Mirage studios. The actual creation of the turtles was (now famously) due to the two friends going out for dinner and a few beers, which led to Eastman drawing some half-cut ideas onto a napkin - a rare case of where the drunken "That's a great idea!" mentality actually paid off.