Satoshi Ishii (石井 慧, Ishii Satoshi, born December 19, 1986) is a Japanese-Croatian judoka and mixed martial artist. Ishii won the gold medal in Olympic Judo at the Beijing 2008 Summer Olympics, a silver medal at the 2006 Asian Games and two All-Japan Judo Championships representing Japan. Ishii made his professional MMA debut at Dynamite!! 2009 losing to fellow Judoka gold medalist Hidehiko Yoshida by unanimous decision, but currently holds a record of 19-8-1.
Ishii is currently under contract with Professional Fighters League.Professional mixed martial artist since 2009, Ishii has also competed for Rizin Fighting Federation and Bellator. Ishii started Judo under the guidance of his father when he was in fifth grade of elementary school. He attended Kokushikan High School and then Kokushikan University in the Department of Physical Education. Ishii won a gold medal at the Junior World Championships on 16 October 2004 in Budapest, Hungary. On 2 December 2006 he won a silver medal at the −100 kg category of the 2006 Asian Games. On April 29, 2006 and 2008, he won the All-Japan Judo Championships in Tokyo, Japan. With him the Japanese team won the World Judo team competition on 17 November 2007 in Beijing, China, this time in the +100 kg division. On August 15, 2008 he won a gold medal at the +100 kg category of the Beijing 2008 Summer Olympics.