The Teenage Mutant Ninja Turtles (often shortened to TMNT or Ninja Turtles) are a fictional team of four teenage anthropomorphic turtles, named after four Renaissance artists, who were trained by their anthropomorphic rat sensei in the art of ninjutsu. From their home in the storm sewers of New York City, they battle petty criminals, evil overlords, mutated animals, and alien invaders while attempting to remain isolated from society. The characters originated in the Teenage Mutant Ninja Turtles comic book before their expansion into a cartoon series, films, video games, toys, and other general merchandise. During the peak of the franchise’s popularity in the late 1980s through the early 1990s, it gained considerable worldwide success and fame.