Ninjutsu (忍術), the art of endurance, is an overarching system of martial arts and tactics used by ninja.

Ninjutsu consisted of many forms of teachings required by the ninja to perform their duties, which included assassinations, espionage, and other covert ops work. Unarmed combat is known as taijutsu, and often incorporates forms from different styles, to be used as the situation demands. Various weapon arts, including kenjutsu (sword) and bojutsu (staff) are essential. Other concepts practiced due to their usefulness are hensoujutsu (the art of impersonation and disguise), bajutsu (equestrianism), and chi-mon (geography). Ninjutsu is often rendered as ninjitsu within TMNT media, due to an outdated romanization of the word from its original Japanese.