María Luz Olier Arenas, known professionally as Mari Luz Olier, is a Spanish actress of theater, television, and voice, as well as a writer and dubbing director. Born in Madrid, she studied Journalism and began her artistic career at a young age, writing serialized novels for radio at nineteen and debuting as a professional theater actress in 1969. Her on-camera work includes appearances in the long-running children's television series Barrio Sésamo, the Spanish co-production of Sesame Street, where she played the character Matilde from 1983 to 1987. She has also appeared in television series such as Hospital Central and Cuéntame.

Olier has built an extensive and prolific career in dubbing, providing Spanish voices for a vast array of characters in anime, live-action films, and television series. Her work in animation includes voicing Meg March and the character Stuffy in the series Little Women and its sequel Little Women II Jo's Boys. She also lent her voice to the title character Dragon in the film Taro the Dragon Boy, Princess Odette in the film Swan Lake, and Marionella in the film Techno Police 21C. Her other notable anime roles include Diana in Maple Town Stories, Lust in Fullmetal Alchemist, and various characters in series such as Robotech and Pokémon.

In addition to her work in anime, Olier is renowned in Spain for being one of the primary voice actresses for a host of acclaimed international performers. She is the regular Spanish dubbing voice for actresses such as Maggie Smith (including her role as Professor Minerva McGonagall in the Harry Potter film series), Kathy Baker, and Jane Curtin. Her extensive dubbing credits encompass a wide range of films and television shows, including roles in Malcolm in the Morning (as the mother, Lois), Gilmore Girls (as Emily Gilmore), and Downton Abbey.

Beyond her work in front of the microphone, Mari Luz Olier has been active as a dubbing director since at least 1985. She has directed the Spanish dubbing for numerous films and television series, including The Crucible, Criminal Minds, and Malcolm in the Middle. She has also shared her expertise as a teacher, conducting seminars and workshops on interpretation and dubbing for various universities and acting unions. Parallel to her performance career, Olier is an accomplished author, having published novels, poetry, and radio dramas, for which she has received literary awards such as the Premio Margarita Xirgu in 2006.