Ryūsuke Shiomi was a Japanese actor and voice actor born on August 29, 1933. His real name was Tadashi Kosho. He was born in Hakodate, Hokkaido, but spent his early childhood in Otaru before moving to Sapporo during elementary school. His career in performance began when he joined a local junior theater group, which led him to pursue acting professionally after moving to Tokyo. Over the years, he was affiliated with several theater companies, including the Radio Tokyo Drama Company and Theatre Echo. He later became the representative of the theatre group Group Eight.

Shiomi possessed a low, gruff voice and a solid physique, traits that often led to him being cast in antagonistic roles in period dramas. His distinctive voice also made him a prolific figure in voice acting, particularly in dubbing foreign television series and films. His performance as Little John in the dubbed version of the American war drama Combat! was highly acclaimed. By the 1970s, he had become a prominent voice actor, regularly appearing in more than ten series at once, including anime and foreign drama dubs.

In the field of anime, Shiomi took on a variety of memorable supporting roles. He played Daizō Ban in the long-running baseball series Kyojin no Hoshi and its film version, Kyojin no Hoshi: Chizome no Kesshōsen. He voiced the villainous General Gurul in the classic super robot series Voltes V. In the film Kaibutsu-kun: Demon no Ken, he played the role of Akuma Daiō Demon. He also portrayed the Hotel Galaxy President in the film Nijūichiemon: Uchū e Irasshai! and the role of God in the series Superbook. Other notable anime roles included Commander Werner in Invincible Steel Man Daitarn 3, Medon in the film version of Umi no Triton, and Adachi Kanchō in The Unchallengeable Daitarn 3. He also contributed to the Ultraman franchise, playing Sakurada Kanchō in both the series and film The Ultraman.

Beyond his on-screen and voice work, Shiomi was also a stage director and educator. He was instrumental in the founding of the theatre group Group Eight, for which he served as representative and regularly directed productions. He also taught at the Tokyo Announce Gakuin, where his students included the notable voice actor Kaneto Shiozawa. Ryūsuke Shiomi passed away on September 14, 1983, at the age of 50 due to cancerous pleurisy. After his death, several of his most famous roles, including General Gurul and Akuma Daiō Demon, were inherited by other voice actors in later productions and video games.