Masutatsu Ōyama (born Choi Yeong-eui; 27 July 1923 – 26 April 1994), commonly known outside Japan as Mas Oyama, was a Korean-Japanese karateka. He was the founder of Kyokushin Karate, considered the first and most influential style of full contact karate.
Source: “Mas Oyama”, English Wikipedia (CC BY-SA 4.0), excerpt