Silvia Sarmentera is a Spanish voice actor known for her extensive work in dubbing foreign-language content, particularly anime and animated series, into Castilian Spanish for the Spanish market. Her career spans several decades and includes a wide variety of prominent roles in internationally renowned franchises. She is frequently engaged to voice characters for productions distributed by major platforms like Netflix and for broadcast on Spanish television.

Sarmentera's filmography is characterized by a broad range of characters, from young heroes to complex antagonists. She provided the Spanish voice for Rebecca Bluegarden, the optimistic and determined protagonist of the science fiction series Edens Zero. In the Kakegurui twin series, a prequel to the popular Kakegurui franchise, she voiced Sachiko Juraku, a student at the elite gambling academy. She also took on the role of Hotaru Tomoe, also known as Sailor Saturn, in the two-part film Pretty Guardian Sailor Moon Eternal, which was released by Netflix in Spain.

Her work also includes roles in classic and long-running anime series. Sarmentera voices Ai Haibara, a key character in the long-running detective series Case Closed, known in Spain as Detective Conan. She was also the Spanish voice for the protagonist Allen Walker in the dark fantasy series D.Gray-man. In the Ghibli film From Up On Poppy Hill, she voiced Miki Hokuto. One of her earlier roles includes providing the voice for Chorke in the anime series Kouchuu Ouja Mushiking: Mori no Tami no Densetsu, which was broadcast in Spain as Mushiking: Los Guardianes Del Bosque.

Beyond anime, Sarmentera has contributed her voice to numerous other projects. This includes roles in various Pokémon series, such as Sonia in Pokémon Journeys: The Series and Corinna in Pokémon Advance. She has also been involved in the Transformers franchise, voicing Thunderblast in the Cybertron series and Skywarp in the more recent EarthSpark series. Her work extends to live-action dubbing as well, for example, voicing the character Bebbie in the film Buscarse la vida en América and Cynthia Mancheno in an episode of Law & Order: Special Victims Unit. Sarmentera has also participated in Spanish-language versions of films like the live-action Fullmetal Alchemist and the animated movie SuperKlaus.

Throughout her career, Sarmentera has frequently collaborated with the same Madrid-based dubbing studios and directors, contributing to the consistency of voices for major franchises in Spain. She has voiced the character Riza Hawkeye across multiple iterations of the Fullmetal Alchemist franchise, including the original anime series, its sequel film Conqueror of Shamballa, and the live-action film adaptation, demonstrating a long-standing association with the role. Her recurring work as Ai Haibara in the various Case Closed films and series also highlights her as the consistent Spanish voice for that character.