The Teenage Mutant Ninja Turtles (often shortened to TMNT or Ninja Turtles) are four fictional teenaged anthropomorphic turtles named after Italian artists of the Renaissance. They were trained by their anthropomorphic rat sensei in the art of ninjutsu. From their home in the sewers of New York City, they battle petty criminals, evil overlords, mutated creatures, and alien invaders while attempting to remain hidden from society. They were created by Kevin Eastman and Peter Laird.

Where did the ninja turtles get their names? Let's have some stream of consciousness first.
To answer the question, consider the following: The Teenage Mutant Ninja Turtles (often shortened to TMNT or Ninja Turtles) are four fictional teenaged anthropomorphic turtles named after Italian artists of the Renaissance. So, the answer is Italian artists of the Renaissance.