Yamaguchi (山口, "mountain entrance/gateway") is the 14th most common Japanese surname. Notable people with the surname include:

• Adam Yamaguchi, American television correspondent and producer
• Akane Yamaguchi (山口 茜, born 1997), Japanese badminton player
• Akihiro Yamaguchi (山口 観弘, born 1994), Japanese swimmer
• Akira Yamaguchi (山口 晃, born 1969), Japanese artist
• Atsushi Yamaguchi (disambiguation), multiple people
• Bidou Yamaguchi (山口 毘堂, born 1970), Japanese Noh mask carver
• Eri Yamaguchi (disambiguation), multiple people
• Eriko Yamaguchi (山口 恵梨子, born 1991), Japanese shogi player
• Erina Yamaguchi (山口 絵里奈, born 1985), Japanese gravure idol
• Gōgen Yamaguchi (山口 剛玄, 1909–1989), Japanese karateka
• Gorō Yamaguchi (山口 五郎, 1933–1999), Japanese shakuhachi musician
• Harukichi Yamaguchi (山口 春吉, 1881–1938), Japanese mob boss
• Hatsuye Yamaguchi (1911-2005), Japanese-American artist and dollmaker
• Hideko Yamaguchi, plaintiff foster mother in Sweden v. Yamaguchi, a famous international family law trial
• Yamaguchi Hisashi (山口 久, 1952–2010), Japanese sumo wrestler
• Hitomi Yamaguchi (山口 瞳, 1923–1995), Japanese novelist and essayist
• Hōshun Yamaguchi (山口 蓬春, 1893–1971), Japanese painter
• Hotaru Yamaguchi (山口 蛍, born 1990), Japanese footballer
• Ichiro Yamaguchi (山口 一郎, born 1980), Japanese musician
• Izumi Yamaguchi (山口 いづみ, born 1954), Japanese actress
• Jun Yamaguchi (山口 淳, born 1967), Japanese composer
• Junya Yamaguchi, Japanese musician
• Kaori Yamaguchi (山口 香, born 1964), Japanese judoka
• Kappei Yamaguchi (山口 光雄, born 1965), Japanese actor and voice actor
• Kayo Yamaguchi (山口 華楊, 1899–1984), Japanese painter
• Kazuhiko Yamaguchi (山口 和彦, born 1937), Japanese film director
• Kazuki Yamaguchi (disambiguation), multiple people
• Kazuma Yamaguchi (山口 一真, born 1996), Japanese footballer
• Kazuo Yamaguchi (山口 一男, born 1946), Japanese sociologist
• Kei Yamaguchi (山口 慶, born 1983), Japanese footballer
• Keiji Yamaguchi (山口 圭司, born 1974), Japanese boxer
• Ken Yamaguchi (山口 健, 1956–2011), Japanese voice actor
• Koichi Yamaguchi (山口 弘一), Japanese bicycle framebuilder
• Kosei Yamaguchi (山口 浩勢, born 1991), Japanese long-distance runner
• Kristi Yamaguchi (born 1971), American figure skater
• Mai Yamaguchi (山口 舞, born 1983), Japanese volleyball player
• Makoto Yamaguchi (山口 真, born 1944), Japanese origami artist
• Mami Yamaguchi (山口 麻美, born 1986), Japanese women's footballer
• Mamoru Yamaguchi (山口 マモル, born 1977), Japanese mixed martial artist
• Marie Yamaguchi (山口 真理恵, born 1989), Japanese rugby sevens player
• Masa Yamaguchi (born 1974), Australian actor
• Masakatsu Yamaguchi, plaintiff foster father in Sweden v. Yamaguchi, a famous international family law trial
• Masakazu Yamaguchi (山口 譲司), Japanese manga artist
• Masao Yamaguchi (山口 昌男, 1931–2013), Japanese anthropologist
• Masaya Yamaguchi (born 1970), American jazz guitarist and music writer
• Masayoshi Yamaguchi (山口 正義, born 1947), Japanese scientist
• Masuka Yamaguchi (山口 尚芳, 1839-1894), Japanese government official
• Mayumi Yamaguchi (山口 眞弓, born 1975), Japanese voice actress
• Megumi Yamaguchi (山口 愛, born 1997), Japanese voice actress
• Mei Yamaguchi (山口 芽生, born 1983), Japanese mixed martial artist and kickboxer
• Michael Yamaguchi, American lawyer
• Misaki Yamaguchi (山口 美咲, born 1990), Japanese swimmer
• Miyako Yamaguchi (山口 美也子, born 1952), Japanese actress
• Moe Yamaguchi (山口 もえ, born 1977), Japanese television personality
• Momoe Yamaguchi (山口 百恵, born 1959), Japanese singer, actress and idol
• Motohiro Yamaguchi (山口 素弘, born 1969), Japanese footballer and manager
• Nana Yamaguchi (山口 奈々, born 1938), Japanese voice actress
• Noboru Yamaguchi (disambiguation), multiple people
• Natsuo Yamaguchi (山口 那津男, born 1952), Japanese politician
• Otoya Yamaguchi (山口 二矢, 1943–1960), Japanese ultranationalist best known for his assassination of Inejiro Asanuma
• Renshi Yamaguchi (山口 廉史, born 1992), Japanese footballer
• Rie Yamaguchi (山口 理恵, born 1986), Japanese voice actress
• Rikako Yamaguchi (山口 立花子, born 1988), Japanese voice actress
• Roy Yamaguchi, Japanese-American chef
• Ryōta Yamaguchi (山口 亮太, born 1969), Japanese anime screenwriter
• Satoshi Yamaguchi (disambiguation), multiple people
• Satyu Yamaguti (山口 左仲, 1894-1976), Japanese parasitologist
• Sayaka Yamaguchi (山口 紗弥加, born 1980), Japanese actress
• Sayoko Yamaguchi (山口 小夜子, 1949–2007), Japanese model and actress
• Sayuri Yamaguchi (山口 小百合, born 1966), Japanese women's footballer
• Seigo Yamaguchi (山口 清吾, 1924–1996), Japanese aikidoka
• Seiya Yamaguchi (山口 聖矢, born 1993), Japanese footballer
• Yamaguchi Sekkei (山口 雪渓, 1644/48 – 1732), Japanese artist
• Senji Yamaguchi (山口 仙二, 1930–2013), Japanese anti–nuclear weapons activist
• Shinji Yamaguchi (山口 真司, born 1996), Japanese footballer
• Shogo Yamaguchi (山口 翔悟, born 1983), Japanese actor
• Shun Yamaguchi (山口 俊, born 1987), Japanese baseball player
• Shunichi Yamaguchi (山口 俊一, born 1950), Japanese politician
• Yamaguchi Soken (山口 素絢, 1759–1818), Japanese painter
• Susumu Yamaguchi (山口 益, 1895–1976), Japanese Buddhist scholar
• Yamaguchi Tadasada (山口 正定, 1843–1902), Imperial Japanese Navy officer
• Taimei Yamaguchi (山口 泰明, born 1948), Japanese politician
• Takahiro Yamaguchi (山口 貴弘, born 1984), Japanese footballer
• Takashi Yamaguchi (山口 隆, born 1953), Japanese architect
• Takashi Yamaguchi (actor) (山口 崇, born 1936), Japanese actor
• Takayuki Yamaguchi (disambiguation), multiple people
• Takeo Yamaguchi (山口 長男, 1902–1983), Japanese painter
• Takeshi Yamaguchi (山口 武士, born 1979), Japanese footballer
• Tamon Yamaguchi (山口 多聞, 1892–1942), Imperial Japanese Navy admiral
• Taro Yamaguchi (山口 太郎, born 1970), Japanese voice actor
• Tatsuya Yamaguchi (disambiguation), multiple people
• Tazuo Yamaguchi, American poet and filmmaker
• Tetsuharu Yamaguchi (山口 哲治, born 1970), Japanese footballer
• Tetsumasa Yamaguchi (山口 徹正, born 1947), Japanese sprint canoeist
• Tetsuya Yamaguchi (山口 鉄也, born 1983), Japanese baseball player
• Toichi Yamaguchi (山口 東一, born 1941), Japanese middle-distance runner
• Tomoko Yamaguchi (山口 智子, born 1964), Japanese actress and voice actress
• Tomomi Yamaguchi, Japanese anthropologist
• Tomomitsu Yamaguchi (山口 智充, born 1969), Japanese comedian, actor and voice actor
• Toshihiro Yamaguchi (山口 敏弘, born 1971), Japanese footballer
• Toshio Yamaguchi (山口 敏夫, born 1940), Japanese politician
• Tsubasa Yamaguchi (山口つばさ), Japanese manga artist
• Tsutomu Yamaguchi (山口 彊, 1916–2010), Japanese national who survived both the Hiroshima and Nagasaki atomic bombings during the Second World War
• Tsuyoshi Yamaguchi (disambiguation), multiple people
• Wally Yamaguchi (1959–1958), also known as Yamaguchi-san, Japanese professional wrestling manager and sports journalist
• Yasushi Yamaguchi (山口 恭史), Japanese video game artist and designer
• Yoko Yamaguchi (山口 洋子, 1937–2014), Japanese lyricist and writer
• Yorifusa Yamaguchi (山口 頼房, born 1959), Japanese film director
• Yoshiharu Yamaguchi (山口 良治, born 1943), Japanese rugby union player
• Yoshiko Yamaguchi (山口 淑子, 1920–2014), Chinese-born Japanese actress and singer
• Yoshinori Yamaguchi (山口 祥義, born 1965), Japanese politician
• Yoshitada Yamaguchi (山口 芳忠, born 1944), Japanese footballer and manager
• Yūdai Yamaguchi (山口 雄大, born 1971), Japanese film director
• Yuki Yamaguchi (山口 有希, born 1984), Japanese sprinter
• Yuko Yamaguchi (山口 裕子, born 1955), Japanese character designer and illustrator
• Yūji Yamaguchi (山口 祐司, fl. 1999–2014), Japanese animator
• Yuriko Yamaguchi (voice actress) (山口 由里子, born 1965), Japanese voice actress
• Yuriko Yamaguchi (sculptor) (born 1948), Japanese-American sculptor
• Yutaka Yamaguchi (山口 泰, born 1940), Japanese businessman and economist
• Zuiho Yamaguchi (山口 瑞鳳, born 1926), Japanese Buddhist scholar and Tibetologist