Bastian Sierich is a German actor and voice artist, born in Hamburg on July 27, 1976, who has built an extensive career in theatre, film, and particularly in dubbing foreign-language productions for the German market. His path to performance began after he was discovered by an agency in Cologne in 1995, leading to his first television roles. He later formalized his training at the Stage School Hamburg, where he studied acting, dance, and singing. Sierich's early career was rooted in theatre, including a long tenure as a permanent ensemble member at the Junges Schauspielhaus Düsseldorf, alongside work in various German television series such as Mein Leben & Ich, Die Wache, and SOKO Leipzig.

While Sierich's voice work spans a wide array of genres, he has become a prominent and prolific figure in German anime dubbing. He is frequently cast in leading and supporting roles, often bringing to life characters with complex or intense personalities. Among his most notable anime roles is the mysterious and powerful demon Diablo in the popular series That Time I Got Reincarnated as a Slime. He also voiced the cunning and bloodthirsty fighter Bill in BEASTARS, a role that showcased his ability to handle characters with a predatory edge. Another significant performance is his portrayal of the manipulative and combat-loving Hisoka in Hunter x Hunter (2011), a character for which his work has been particularly praised by German audiences.

His extensive filmography includes a wide variety of other anime titles. He is the voice of the loyal Loki in Fairy Tail, the rival Vali Lucifer in High School DxD, and the serene Makoto Shimada in Haikyu!!. In the series Black Butler, he took on the role of the enigmatic Snake across multiple installments, including Book of Circus, Book of Murder, and Book of the Atlantic. His repertoire further demonstrates his range with roles such as Yutaka Zaito in Dragon Pilot: Hisone and Masotan, Takuma Akutsu in Val x Love, Kanji Kageyama in Twittering Birds Never Fly: The Clouds Gather, Kaname Mozunoto in 7SEEDS, Joujirou Takajou in Charlotte, and Tadashi in the horror OVA GYO: Tokyo Fish Attack. He is also the German voice of Kiyotaka Ayanokōji in Classroom of the Elite and has voiced characters in major franchises like Dragon Ball Super as Jaco and Attack on Titan The Final Season as Marcel Galliard.

A recurring and notable aspect of Sierich's career is his work as the official German dubbing voice for the American actor Rami Malek. He has dubbed Malek in numerous high-profile films and series, including the actor's Oscar-winning performance as Freddie Mercury in Bohemian Rhapsody, the title role in Mr. Robot, and as the villain Lyutsifer Safin in the James Bond film No Time to Die. Beyond anime and this signature dubbing role, Sierich's voice is heard in a vast range of other projects, from live-action series like S.W.A.T. and Star Trek: Discovery to films such as Fast & Furious 9 and video games. He is also active as an audiobook narrator.