Mas Oyama, South Korean-Japanese martial artist (d. 1994)
Masutatsu Ōyama (大山 倍達, Ōyama Masutatsu, born Choi Yeong-eui (Hangul: 최영의 Hanja: 崔永宜); June 4, 1923 – April 26, 1994), more commonly known as Mas Oyama, was a karate master who founded Kyokushin Karate, considered the first and most influential style of full contact karate. A Zainichi Korean, he spent most of his life living in Japan and acquired Japanese citizenship in 1968.