Gerd Duwner was a German actor and voice actor, active in the industry from the 1950s until his death in 1996. He completed his classical acting training in Berlin and performed in various theaters in Berlin and Stralsund early in his career. Starting in 1955, he increasingly focused on dubbing foreign-language films and television series, becoming one of the most sought-after voice actors in Germany. The Deutsche Synchronkartei, a German dubbing database, lists over 2000 dubbing jobs for him.

In the realm of anime and animated series dubbed into German, Duwner contributed his voice to several notable productions. He is known for providing the German voice for the character Flip in the 1989 animated film Little Nemo - Adventures in Slumberland, for which the German synchronization was completed in 1992. He also voiced the character 006 / Chang Changku in the film Cyborg 009 Gekijō Ban: Chō Ginga Densetsu. His other anime voice roles, as documented by the Anime News Network, include a butler in Hana no Ko Lunlun, the slave trader Dom in Huckleberry no Bōken, various roles in Kimba the White Lion such as Gelbe Schildkröte and Snakely, Guillaume in The Perrine Story, and a priest in Raccoon Rascal.

Beyond anime, Duwner's voice became widely recognized in Germany through numerous other dubbing roles. He was the long-standing German voice of Ernie in the children's television series Sesame Street from 1973 until his death. He also served as the standard German voice actor for several prominent actors, including Mickey Rooney, Danny DeVito, Oliver Hardy in later dubs, and Chico Marx. Among his many other dubbing credits are Barney Rubble in The Flintstones, Bosley in Three's Company, and roles for actors like Ned Beatty, Charles Durning, and Burt Young. In addition to his voice work, Duwner appeared as an on-screen actor in numerous German and international film and television productions between 1959 and 1993, with titles such as The Old Shatterhand, Kommissar X - In den Klauen des goldenen Drachen, and Reunion to his credit.