Seiya Yamanaka is a Japanese actor and voice actor born on November 19, 1965, in Hiroshima Prefecture, Japan. Standing 172 cm tall, he is affiliated with the talent agency Nexeed.citation:1citation:5 Yamanaka built his foundation in performance by training at the Engeki Shudan En training institute and the Subaru acting school, which led to an early career in theater with companies such as Subaru and Production Ace.citation:1citation:5

His extensive voice acting portfolio includes a variety of roles in anime, video games, and dubbed foreign media. In animation, his credits include Russell in Date A Live III, a Senator in Helck, Taig in The World's Finest Assassin Gets Reincarnated in Another World as an Aristocrat, and roles in Wandaba Style, Red Cat Ramen, and The Dinner Table Detective.citation:1citation:5citation:6citation:. Done It in the US animated series Sonic Prime.citation:6 In a notable live-action dubbing role, he provided the Japanese voice for Dr. Richard Smith in the Philippine series Voltes V: Legacy.citation:2citation:6

Yamanaka has also worked extensively in video games, lending his voice to characters such as George Tarleton, also known as MODOK, in Marvel's Avengers, as well as roles in Fallout 4 and Shironeko Project.citation:1citation:5 His dubbing work for international films and television series is substantial, including the Japanese-language versions of Another Round, Papillon, Kandahar, NCIS, and The Boys.citation:1citation:5

Beyond voice acting, Yamanaka has appeared in Japanese TV dramas, including Sasurai Keiji Ryojo-hen and Sono Toki, Heart wa Nusumareta.citation:1citation:5 He remains active in stage productions, taking on roles in classic Shakespearean plays such as Othello, Hamlet, A Midsummer Night's Dream, and The Merchant of Venice.citation:1citation:5 In addition to performing, he serves as a lecturer at Nihon Kogakuin College, where he teaches aspiring performers.citation:1