Masato Yamanouchi was a Japanese voice actor, actor, and narrator born on April 3, 1929, in Tokyo, Japan. He passed away on April 7, 2003, at the age of 74 due to complications from lung cancer. His real name was Mikio Yamauchi. Over the course of his extensive 58-year career, he was reportedly involved in more than 20,000 works and provided Japanese dubbing for over 3,000 films.

Yamanouchi began his career in 1945 when he joined the NHK Tokyo Broadcasting Company, where he hosted a radio show and made his voice acting debut. His early training was centered on dramatic reading, which he initially performed in coffee shops. In 1949, he co-founded the Broadcast Expression Education Center with linguist Haruhiko Kindaichi, an institution focused on the preservation of the Edo language and the art of dramatic reading, which became the first recitation school in Japan. He received the NHK Broadcasting Operation Director's Award and the Arts Festival Award for Excellence in drama in 1975. After leaving NHK in 1977, he worked for K Production before becoming a freelancer.

Yamanouchi's career was marked by a vast number of roles in anime and dubbing. In anime, he is well-known for several significant parts. He voiced the character Jakounezumi, also known as Muskrat, in the series Tanoshii Moomin Ikka: Moomin Tani no Suisei (Comet in Moominland). He played Dr. Kōtarō Azuma in the 1973 series Casshan. He took on the role of Santa Claus in Shōnen Santa no Daibōken. In the series Document Taiyou no Kiba Dougram (Fang of the Sun Dougram), he voiced Donan Cashim. He also voiced the Grand Father character in Mirai Shōnen Conan Tokubetsu-hen - Kyodaiki Gigant no Fukkatsu (Future Boy Conan: The Resurrection of the Giant Machine). His role as Professor Hayashi was in the film Maken Liner-0011 Henshin Seyo!!. In the classic 1963 film The Little Prince and the Eight-Headed Dragon (Wanpaku Ōji no Orochi Taiji), he played the role of Wadatsumi. He was the voice of Sandada in the 1995 movie Catnapped! (Catnapped! The Movie). He also played Hansuke Murai in Seishun Anime Zenshu. In the OVA Armored Trooper Votoms: The Heretic Saint (Armored Trooper Votoms: Brilliantly Shining Heresy), he voiced Viachevlav da Montewells.

Beyond these specific roles, Yamanouchi had many other notable anime credits. He was the voice of Grandpa and Dr. Lao in the 1978 series Future Boy Conan. He voiced the antagonist Black Ghost in the 1966 film Cyborg 009. Later in his career, he played Emperor Dornkirk in The Vision of Escaflowne and the Foreign Minister in the 1995 film Ghost in the Shell.

A significant portion of Yamanouchi's work was in dubbing foreign films and television series. He was particularly known as the regular Japanese dubbing voice for actors Tyrone Power and Montgomery Clift. Some of his prominent dubbing roles included Leonard Vole for Tyrone Power in Witness for the Prosecution and Private Robert E. Lee Prewitt for Montgomery Clift in From Here to Eternity. He also dubbed many other famous films, providing voices for actors such as Anthony Hopkins in Meet Joe Black and Amistad, Patrick McGoohan in Braveheart, and George C. Scott in 12 Angry Men. His work also extended to television, where he was the voice of the Cigarette Smoking Man in The X-Files.