Isaak Dentler is a German actor, voice actor, and theater director recognized for his work in live-action film and television as well as for providing German dubbing voices for numerous anime and international productions. Born in Ulm in 1980, Dentler initially completed an apprenticeship as a bank clerk before pursuing his passion for performance. He went on to receive his acting training at the Schauspiel Studio Frese in Hamburg, a traditional drama school in Germany.

Dentler built a strong foundation in classical theater early in his career. He joined the ensemble at the Stadttheater Gießen for five years before becoming a permanent ensemble member at the Schauspiel Frankfurt in 2009, where he has remained a prominent figure. His stage work has seen him collaborate with numerous acclaimed directors, including Michael Thalheimer, Karin Henkel, Sebastian Hartmann, and David Bösch. In addition to his ensemble work, he has also stepped into the role of director, creating and performing in solo pieces such as Werthers Leiden and Kohlhaas.

As a voice actor, Dentler is perhaps best known for his long-standing association with the Sword Art Online franchise. He is the German voice of the character Klein (whose real name is Ryoutarou Tsuboi). Dentler has voiced Klein across nearly the entire series, including the original Sword Art Online, Sword Art Online II, the Extra Edition special, the film Ordinal Scale, and subsequent seasons like Alicization and War of Underworld. Beyond this franchise, his notable anime roles include Kouki Mimura in Assassination Classroom and Yahiro Samukawa in Guilty Crown. His voice work extends beyond Japanese animation; he has also dubbed roles for international live-action films, such as Arnold Reyes’ character in Graceland and Robert de Hoog’s character in Nova Zempla.

Dentler’s career also encompasses significant work in German film and television. He is a familiar face to crime drama audiences, having appeared from 2014 to 2024 as an assistant detective on the Frankfurt-based Tatort series. His other television credits include roles in the Netflix series 1899 and Dark, as well as parts in shows like SOKO Köln and Der Staatsanwalt. He is also an established voice for documentary series, serving as a narrator for ZDF History and Kulturzeit on 3sat. His extensive voice portfolio includes numerous audiobooks and radio dramas, including collaborations with author Navid Kermani.