Thierry Janssen is a Belgian actor, born on November 29, 1972, who is primarily known for his extensive work in dubbing, providing the French-language voices for numerous characters in anime series and films. He is a graduate of the Institut des Arts de Diffusion (IAD) in Louvain-la-Neuve, Belgium, from which he earned his degree in 1995. Before focusing on acting and dubbing, he also worked as a television and radio host in Belgium, presenting programs such as Saka Saka on Fun Radio and À nous les studios on Club RTL.

His career is deeply rooted in the performing arts, with significant experience in theatre. Janssen has performed in a wide range of classic and contemporary plays, including works by Shakespeare, Victor Hugo, and Dario Fo. He has also contributed as an author and adapter for the stage, writing plays like Facteur humain and Folles Funérailles, and adapting literary classics such as The Lord of the Rings and The Adventures of Tom Sawyer for theatrical production.

In the realm of anime dubbing, Thierry Janssen has built an impressive and diverse portfolio, becoming a familiar voice to French-speaking fans of the genre. Among his most prominent roles are several long-running characters in major franchises. He is notably the voice of Choji Akimichi and Kankuro in the Naruto, Naruto Shippuden, and Boruto: Naruto Next Generations series, a role he has performed for many years across the television shows and numerous films. He is also one of the primary voices in the French dub of One Piece, where he has voiced a multitude of characters, including several major antagonists such as Captain Morgan, Don Krieg, Wapol, and the iconic Crocodile.

Janssen holds two key, long-standing roles in the Detective Conan franchise. He voices both the child Genta Kojima, one of Conan's friends, and Professor Hiroshi Agasa, the inventor who aids Conan. He has performed these roles consistently in the television series and in numerous theatrical films, including the 2021 film Detective Conan: The Scarlet Bullet. His other notable anime credits include the role of Santori le Pic and Lord Brangoire in the series Radiant, Kartatz in In the Land of Leadale, Shaka in Saint Seiya: The Hades Chapter - Sanctuary, Bill Cipher in Gravity Falls, Kai in Beyblade, Dr. Crowler in Yu-Gi-Oh! GX, and Splinter and Casey Jones in the Teenage Mutant Ninja Turtles series.

Beyond animation, Thierry Janssen is highly active in dubbing for live-action series and films, lending his voice to actors such as Salvatore Esposito as Gennaro Savastano in the Italian series Gomorra and Matt Lucas as Nardole in Doctor Who. He is also a prolific narrator for audiobooks, having recorded works by major authors including J.R.R. Tolkien's The Lord of the Rings and The Silmarillion, as well as novels by Fred Vargas and Lars Kepler. His work demonstrates a versatile career spanning stage, screen, and voice acting.