En no Ozunu, also En no Ozuno, Otsuno (役小角) (b. 634, in Katsuragi (modern Nara Prefecture); d. c. 700–707) was a Japanese ascetic and mystic, traditionally held to be the founder of Shugendō, the path of ascetic training practiced by the gyōja or yamabushi.

He was banished by the Imperial Court to Izu Ōshima on June 26, 699, but folk tales at least as old as the Nihon Ryōiki (c. 800) recount his supernatural powers and exploits.

He also referred to by the name En no Gyōja (役行者, "En the ascetic"), En no Ubasoku (役優婆塞, "En the Layman") , or under the full name En no Kimi Ozunu, where Kimi (君) is his kabane or titular name.