Sissi Martins is a Portuguese voice actor known for her work in the European Portuguese dubbing of numerous animated films and television series. Her extensive career encompasses a wide range of characters in productions for both cinema and television, with a significant body of work in anime and animated content aimed at younger audiences.

Martins has a particularly prominent portfolio in the Portuguese dubbing of the long-running Pokémon anime franchise. She is the voice of the character Serena across multiple installments of the series. Her credits for this role include the television series Pokémon A Série XY: Desafio em Kalos, Pokémon A Série XY: Uma Nova Mega-Aventura, and Pokémon Jornadas Supremas: A Série. She also provided the voice for Serena in several Pokémon films, such as Pokémon O Filme: Hoopa e o Duelo Lendário, and, as noted by the user, the films featuring Volcanion and Diancie, where she continued her role as the character. In addition to Serena, she has also voiced the character Alexa within the Pokémon series.

Beyond Pokémon, Martins's voice work includes a vast array of leading and supporting roles in other major animated properties. Her dubbing credits feature the title character Sunny Starscout in My Little Pony: Uma Nova Geração and its related series, Raya in both Raya e o Último Dragão and Era Uma Vez Um Estúdio, and Poppy in Trolls 3: Todos Juntos!. She has also voiced key characters such as Dolores in Encanto, Velma Dinkley in Scooby!, Moxy in UglyDolls, and Bela in both the 2017 live-action film A Bela e o Monstro and Ralph vs Internet. Her television work is equally extensive, including roles like Marcy Wu in Anfibilândia, Cintilante (Glimmer) in She-Ra e as Princesas do Poder, April O'Neil in O Despertar das Tartarugas Ninja, and the title character Steven Universe in the Portuguese dub of that series. She has also voiced Marceline in Hora de Aventuras and characters in long-running series such as Naruto Shippuden and O Incrível Mundo de Gumball.

Throughout her career, Martins has frequently collaborated with a consistent group of Portuguese voice actors, indicating regular work with specific dubbing studios. In the Pokémon franchise, her work often places her alongside Raquel Rosmaninho (voice of Ash Ketchum and Jessie), André Lourenço (Clemont), and Mário Santos (Meowth and the Narrator). Many of these productions, including the Pokémon series and films, are dubbed by the studio Cinemágica.

Martins's notable achievements include a prolific career with over ninety credited dubbing participations, showcasing her versatility across film and television. Her work spans major Hollywood animated features, ensuring that Portuguese audiences receive localized versions of globally recognized characters. She has also contributed to the musical aspect of dubbing, being responsible for the song Destinos Rivais and providing singing voices for characters in projects like Dead End: Parque Paranormal.