Isabel Fernández Avanthay is a Spanish voice actor known for her work in dubbing foreign productions into European Spanish, particularly in the realm of animation and anime. She has been active in the dubbing industry for several decades, with credits spanning from the 1990s to the present day.

Fernández Avanthay is recognized for her long-standing association with the Sailor Moon franchise. In the 1990s anime series, she provided voices for numerous secondary characters in Sailor Moon SuperS, including various Remones and other monster-of-the-week roles, as well as Ikuko Tsukino, Usagi's mother. She notably returned to the franchise to voice a principal character, Makoto Kino, also known as Sailor Jupiter, in the Netflix film Pretty Guardian Sailor Moon Eternal, which was released in Spain in 2021. This production saw her alongside many other actors from the original 1990s Spanish dub cast.

Beyond her iconic role in the Sailor Moon universe, Fernández Avanthay has an extensive list of credits in other major anime series. Her work includes voicing Naoko Akagi in the Netflix redub of Neon Genesis Evangelion and its accompanying film. She has also been a frequent voice in the Pokémon anime, taking on various roles across different series and seasons, such as Dr. Anna, Andi, Lindsey, and the character Hermione in the Diamond & Pearl series. Her other anime credits include roles in Case Closed (as Shizuka Hattori), D.Gray-man (as Eliade), Digimon Fusion (as Lilamon), Saint Seiya (as Miho), and Super GALS! (as Kiyoka Kotobuki).

In addition to her extensive anime work, Fernández Avanthay's voice acting career encompasses a wide range of other genres. She is the Spanish voice for characters in Western animation and live-action productions, including various roles in the DC animated universe, such as being the second voice of Harley Quinn in Batman: The Animated Series and Superman: The Animated Series, as well as in the film Batman Beyond: Return of the Joker. Her work also extends to video games; she is the European Spanish voice of the AI Athena in the popular game Overwatch. Her film dubbing credits include the 2005 movie Dark Water and the 2011 film Priest. Among her earliest documented credits is the 1991 film The Refrigerator, where she voiced multiple roles.

Throughout her career, Isabel Fernández Avanthay has built a reputation as a versatile and active figure in Spanish dubbing, contributing her voice to a vast array of characters across anime, animation, and live-action media.