Jan Koester is a German actor and voice artist, born on December 29, 1953, in Braunschweig, Germany. His career in performance began in childhood when he was discovered for film at the age of ten. He is widely recognized for his work in both on-screen and voice acting roles.

Koester's career encompasses a broad range of performance. He has appeared in numerous German film and television productions since the 1960s, including a notable role as Peter, the goatherd, in the 1965 film adaptation of Heidi. His work has extended to the stage, with engagements at prominent venues such as the Münchner Kammerspiele and the Bavarian State Opera. In addition to acting, he has been active as a dialogue director and voice actor for German dubs of international productions.

Within the realm of anime and animation for the German market, Jan Koester is known for his voice work in several popular series. He provided the German voice for the character Boo Jack in the second One Piece film, One Piece: Nejimaki Shima no Bōken, which was dubbed for German release in 2011. His other notable anime voice credits include roles in the Dragon Ball Z and Digimon franchises, having voiced characters such as Raiti and Bibidi in Dragon Ball Z and Piximon in Digimon. Beyond these, his voice can be heard in series like Pokémon.

Koester has also made significant contributions to audio literature. In 1995, he and his wife, Ernie Wilhelmi, founded the NOA NOA Hörbuchedition, a publishing house dedicated to audio books and radio plays. Through this label and his broader work, he has been involved as a narrator and director in numerous audio productions.