Saitō Musashibō Benkei , popularly known by the mononym Benkei, was a Japanese warrior monk (sōhei) who lived in the latter years of the Heian Period (794–1185). Benkei led a varied life, first becoming a monk, then a mountain ascetic, and then a rogue warrior. He later came to respect and serve the famous warrior Minamoto no Yoshitsune, also known as Ushiwakamaru. He is commonly depicted as a man of great strength and loyalty, and a popular subject of Japanese folklore showcased in many ancient and modern literature and productions.

Sōhei were Buddhist warrior monks of both classical and feudal Japan. At certain points in history, they held considerable power, obliging the imperial and military governments to collaborate.