Guy Chapellier is a French actor who is primarily known for his extensive work in dubbing, lending his voice to numerous live-action and animated characters for French-language versions of films and television series. His career in dubbing began after initial work in theatre and on-screen acting roles during the 1970s. He has since become a very active figure in the field, recognized as the regular French voice for several prominent American actors, including Scott Bakula, William Fichtner, and Eric Roberts.

In the realm of animation, Chapellier has contributed his voice to a variety of projects. A notable early role was providing the French voice for the character Seiya in several episodes of the anime series Saint Seiya (known in French as Les Chevaliers du Zodiaque), temporarily replacing the regular voice actor. He is also the voice behind the character Ryu in the French dub of the Fighter II: The Animated Movie. Another significant voice role is that of Admiral in the 2003 Pixar film Finding Nemo. Since 2005, he has been the French voice for both Roger the alien and Klaus the goldfish in the long-running animated series American Dad!.

Chapellier's involvement with major franchises extends to his work as the second French voice of the Disney character Hades across various media, and as the voice of Wilhuff Tarkin in the Star Wars: The Clone Wars animated series. While he voiced Kozo Fuyutsuki in the Rebuild of Evangelion film series, information regarding his specific involvement in the final film, Evangelion: 3.0+1.0 Thrice Upon a Time, is not available in the accessible records of his voice work. His career also encompasses voice work in video games, such as the Mass Effect trilogy and the Batman: Arkham series, as well as extensive work as a narrator for documentaries and audiobooks.