Shōhei Yamaguchi is a Japanese voice actor born on August 16, 1985, in Nagasaki Prefecture, Japan. He is affiliated with the talent agency Wonder Space. Yamaguchi trained at the Yoyogi Animation Institute Fukuoka school and is a graduate of the Mausu Promotion attached actor training school.

Yamaguchi began his voice acting career with small roles in the mid-2000s, with one of his earliest appearances being a student in the anime series sola in 2007. Over the following years, he built a steady career taking on supporting roles and voicing various characters in numerous popular series. His body of work includes many such supporting appearances in major titles, such as a police officer in Steins;Gate, a student in A Certain Scientific Railgun, and various characters in A Certain Magical Index II.

Among his more prominent anime roles, Yamaguchi voiced Ryunosuke Yamaoka in the critically acclaimed jazz-infused coming-of-age story Kids on the Slope (Sakamichi no Apollon). He played Win Chao in the 2016 supernatural action series Bloodivores. In the short-form anime series Love is Like a Cocktail (Oishinbo wa Kekkon ni Natte Kara), which began airing in 2017, he provided the voice for Lemon, the personified bartender who serves the main character. In the 2024 anime series Loner Life in Another World, Yamaguchi voiced the character Gatek. His other notable roles include Mitsugu in the motion comic Chocolate Mansion, Shen Chong in the Chinese-Japanese co-production The Outcast, the manager in Netsuzou Trap, and the character Thunder in the drama CD series Otenki Sentai How Weather. He also played the role of Hotaru's ex-boyfriend in the series Netsuzou Trap.

Yamaguchi has also lent his voice to several video games. He voiced Tomohiro Okawa in Corpse Party: Book of Shadows and played the character Shito Watari in the game Ryusei Halation. His other game credits include roles in Way of the Samurai 4, the Ken to Mahou to Gakuen Mono series, and a minor role in Yakuza 3.

Beyond animation and games, his career has been diverse. He has worked on numerous audio books, including narrating titles such as The World's Easiest Way to Increase Hair Density and reading Japanese versions of several volumes of the Ikebukuro West Gate Park series. He has also been involved in motion comics, dubbing for foreign television dramas, stage acting, and commercial narration.