Mari Yokoo is a veteran Japanese voice actress and narrator from Tokyo, born on February 21, 1952. Her real name is Mari Akiya. She began her career after graduating from the Theatre Echo Acting School. Over the decades, she has been affiliated with several agencies, joining Sigma Seven in April 1997, where she remains.

Yokoo's career took off in the early 1980s with prominent roles in influential anime series. She is known for her versatile and recognizable voice, which has been described as having a calm, sometimes robotic quality that allows her to portray a wide range of characters, from affectionate mothers and nurturing figures to mysterious or antagonistic roles. This range is evident in her work, which spans from the 1980s to the present day.

Her extensive filmography includes many of the roles specified. In the mecha genre, she is known for her performances as Elchi Cargo in Combat Mecha Xabungle (1982), Musy Poe in Aura Battler Dunbine (1983), and Julia Asuka in Blue Comet SPT Layzner (1985). Later mecha roles include Natasha Zabigov in Mobile Fighter G Gundam (1994) and Shora in After War Gundam X (1996).

Yokoo is also recognized for her work in long-running and classic series. She is perhaps best known as the second voice of Suneo's mother, Mrs. Honekawa, in the beloved series Doraemon, a role she held for 13 years from 1984 to 2005. She also played multiple roles in the 1988 version of Osomatsu-kun, voicing both the mother, Matsuyo Matsuno, and one of the sons, Ichimatsu Matsuno. In The Jungle Book: Shōnen Mowgli (1989-1990), she voiced the character Luri. Another significant role from this era was as the narrator for the popular fantasy adventure Magical Circle Guru Guru (1994).

Her work continued through the 1990s and 2000s with roles in series such as the OVA Dragon Slayer (1992) as Felicia, Tekkaman Blade (1992-1993) as Feng-Li, Virgin Fleet (1998) as Hatsuki Fujiwara, and in Haré+Guu (2001) as Bell. In the 2000s, she took on roles in Speed Grapher (2005) as Kaoru Koganei, FireStorm (2003) as Ruth Miller, and the video game Onimusha: Dawn of Dreams (2006) as Yodo.

In more recent years, Yokoo has continued to be active, demonstrating her longevity in the industry. She voiced Fumio Daimido in the Food Wars! series (2015-2017), O-Tomi in Dai-Shogun – Great Revolution (2014), and Mari Tateo in Shirobako (2014). Her recent work includes roles in Skip and Loafer (2023) as Mitsumi's grandmother, Terminator Zero (2024) as The Prophet, and narration for MIRU: Paths to My Future (2025).

Beyond anime, Yokoo is an accomplished narrator for television programs, commercials, and documentaries, making her a familiar presence in Japanese media. She has also lent her voice to numerous foreign film dubs. In addition to her performance work, she is dedicated to teaching and mentoring future voice actors as an instructor at the Sigma Seven Voice Acting School and various cultural centers, considering novel readings to be her life's work.