Yoko Soumi is a Japanese actress and voice actress born on May 31, 1962, in Niigata Prefecture. She began her career as a stage actress in the late 1980s before transitioning into voice work in the early 1990s. Throughout her career, she has been affiliated with Mausu Promotion for nearly three decades before moving to Kakehi Production in 2022. She is also a long-time member of the theatrical group AUN, where she has performed in numerous stage productions, including adaptations of Shakespeare.

Soumi is widely recognized for her rich, low vocal register and ability to portray a broad range of characters, including strong-willed women, maternal figures, and young boys. She has amassed an extensive list of credits in anime, video games, and dubbing for foreign films and television series. One of her most acclaimed anime roles is Olivier Mira Armstrong, the formidable leader of the Briggs Army, in Fullmetal Alchemist: Brotherhood. Additional notable roles include the young shaman Lyserg Diethel in both the 2001 and 2021 versions of Shaman King, Atsuko Urameshi in Yu Yu Hakusho, Zorin Blitz in Hellsing Ultimate, Kusunoki in Lycoris Recoil, and Elizard in A Certain Magical Index III. Her filmography also features roles such as Buzam A. "B.C." Calessa in the Vandread series, Ayla V. Roznovsky in Battle Athletes Victory, Nevola in Mobile Suit Gundam: The Witch From Mercury, and Queen Serenity in the live-action Pretty Guardian Sailor Moon series.

In addition to her anime work, Soumi is a prolific voice actress for dubbing, serving as the established Japanese voice for several Hollywood actresses. She is best known as the regular dub voice for both Cameron Diaz and Sandra Oh, providing the Japanese dialogue for Diaz in films like Charlie's Angels, My Best Friend's Wedding, Bad Teacher, and The Sweetest Thing, as well as for Oh in series such as Grey's Anatomy and Killing Eve. Her other dubbing credits include providing the Japanese voice for Catherine Zeta-Jones in Ocean's Twelve, Connie Nielsen in Gladiator, and Sandra Bullock in Murder by Numbers. She has also voiced characters in animated films, such as May Parker in Spider-Man: Into the Spider-Verse.

In the video game industry, her credits include the role of Ayame in the Tenchu series, Drace in Final Fantasy XII, Oyu in Onimusha 2: Samurai's Destiny, and Tokiko Shigure in AI: The Somnium Files – Nirvana Initiative. Despite a long and successful career, there is no public record of major awards won by Soumi, though she is celebrated for her longevity and versatility in the industry.