The Teenage Mutant Ninja Turtles (or simply Ninja Turtles) are a fictional team of four teenage anthropomorphic turtle

Turtle

Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...

s, who were trained by their anthropomorphic rat sensei

Sensei

' is a Japanese word that basically means "person born before another." In general usage, it means "master" or "teacher," and the word is used as a title to refer to or address teachers, professors, professionals such as lawyers, CPA and doctors, politicians, clergymen, and other figures of authority...

 in the art of ninjutsu

Ninjutsu

or may be:*the arts associated with espionage and assassination in feudal Japan, see Ninja*modern schools of martial arts claiming to be based in these traditions, see Modern Schools of Ninjutsu*fictional depictions, see Ninja in popular culture...

 and named after four Renaissance artists. From their home in the storm sewers of New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

, they battle petty criminals, evil megalomania

Megalomania

Megalomania is a psycho-pathological condition characterized by delusional fantasies of power, relevance, or omnipotence. 'Megalomania is characterized by an inflated sense of self-esteem and overestimation by persons of their powers and beliefs'...

cs, and alien invaders, all while remaining isolated from society

Society

A society, or a human society, is a group of people related to each other through persistent relations, or a large social grouping sharing the same geographical or virtual territory, subject to the same political authority and dominant cultural expectations...

 at large. The characters initially appeared in comic book

Comic book

A comic book or comicbook is a magazine made up of comics, narrative artwork in the form of separate panels that represent individual scenes, often accompanied by dialog as well as including...

s before being licensed for toys, cartoons, video games, films, and other merchandise.