Marie Ōi is a Japanese voice actress from Tokyo, born on July 23, who is affiliated with the agency 81 Produce. Her career is marked by a high degree of versatility, allowing her to portray a wide range of characters, from young children to elderly women, with a particular frequency in roles such as mothers, teachers, and other supporting characters.

Ōi pursued a diverse educational path, studying piano and vocal performance from a young age at a music-oriented elementary school, and later learning the oboe and participating in choir during her secondary education. Despite her strong background in the arts, she went on to earn a university degree in pharmaceutical sciences and is a licensed pharmacist, a unique qualification that she occasionally reflects on as influencing her approach to acting. She is a graduate of the first generation of the Media Force training school.

She made her professional debut in the early 2010s, with her first credited anime role being a shop clerk in the 2012 series Polar Bear Cafe. Since then, she has built an extensive and prolific resume across television anime, animated films, video games, and foreign language dubbing.

Among her many anime television roles, she has played Miwako Honda in Tomica Hyper Rescue Drive Head Kidō Kyūkyū Keisatsu in 2017 and provided the voice of Koharu Obāchan in Hakata Mentai! Pirikarako-chan in 2019. Her filmography includes appearances in numerous major productions. She has had multiple roles in the popular series SPY×FAMILY, including characters such as Karen and Gram Gretcher. Other notable television credits include characters in Summer Time Rendering, The Apothecary Diaries, Frieren: Beyond Journey's End, Oshi no Ko, and Vinland Saga Season 2. Her work also extends to theatrical films such as SPY×FAMILY CODE: White and the Berserk: The Golden Age Arc trilogy.

In addition to anime, Ōi is an active voice actor in video games, with roles in high-profile titles like Final Fantasy VII Rebirth, the Ys series, and Project Sekai: Colorful Stage! feat. Hatsune Miku. She is also a prolific figure in the field of dubbing, providing Japanese voices for characters in foreign films and television dramas, including works like Guardians of the Galaxy Vol. 3 and the series Marvel's Inhumans.

Throughout her career, Ōi has been recognized for her reliability, vocal flexibility, and consistent presence in the voice acting industry.