Ishii (石井, "stone well") is a Japanese surname. Notable people with the surname include:
David Ishii (born 1955), Japanese-American golferHiroshi Ishii (computer scientist), professor at the Massachusetts Institute of TechnologyHiroshi Ishii (golfer) (born 1941), Japanese golferKan Ishii (born 1921), Japanese composer, and the brother of composer Maki IshiiKatsuhito Ishii (born 1966), Japanese film directorKazuhisa Ishii (born 1973), Japanese baseball playerKazuyoshi Ishii (born 1953), Japanese master of Seidokan Karate and the founder of the K-1 fighting circuitKen Ishii, techno DJ and producer from TokyoKikujiro Ishii (1866–1945), Japanese diplomat who negotiated the Lansing-Ishii AgreementKoichi Ishii, video game director for the Square Enix corporation. He is credited for creating the Mana seriesKouji Ishii (born 1960), Japanese voice actor (real name Kōzō Ishii)Kunio Ishii (born 1941), professional Go playerMaki Ishii (1936–2003), Japanese composer, and the brother of composer Kan IshiiMario Alberto Ishii (born 1951), Argentine politician of Japanese origin. Currently mayor of José C. Paz County in the Buenos Aires province of ArgentinaSatoshi Ishii (born 1986), Japanese judoka and mixed martial arts fighterSatsuki Ishii, vocalist of Japanese rock group, HakkaShigemi Ishii (born 1951), Japanese footballerShiro Ishii (1892–1959), military physician who created and ran Japan's biological warfare programSogo Ishii (born 1957), Japanese film directorSusumu Ishii (1924–1991), second kaicho (Godfather) of the Inagawa-kai yakuza gang in JapanTakashi Ishii (film director) (born 1946), Japanese film director and screenwriterTakashi Ishii (baseball) (born 1971), Japanese baseball pitcher and coachTakeo Ishii (born May 3, 1947), Japanese yodelerTakuro Ishii (born 1970), professional baseball player, and husband of former J-Pop singer Azusa SenouTatsuya Ishii (born 1959), Japanese singer, songwriter, artist, and industrial designerTeruo Ishii (1924–2005), Japanese film directorTomohiro Ishii (born 1975), Japanese professional wrestlerTomiko Ishii (born 1935), Japanese actressVania Ishii (born 1973), Japanese-Brazilian judokaYasushi Ishii (born 1970), Japanese singer and composerJ.T. Ishii (born 1984), professional cab driver