While still in drama school, he debuted to play the lead in
Joseph Vilsmaier's '''', alongside actress
Nina Hoss. The critically acclaimed film tells the story of young Leo Knie, a young German in the 1930s who resists the seduction of Adolf Hitler and instead of going to war, struggles with his own personal life. After the film's success, Ketnath continued his studies and work in the theater in Munich. He also participated in several films and series as a protagonist or guest actor, in numerous national projects and also in international co-productions, such as
Minona, between Germany, France, and Russia, which tells the personal life of
Ludwig van Beethoven. In 1998, the actor financed his university studies by being part of the main cast in the prime time series
Klinikum Berlin Mitte – Leben in Bereitschaft, where he played Dr. Daniel Thies for three consecutive seasons. The series was the German version of
ER and popular in several European countries. In 2001, he was part of the
Emmy Awards-winning miniseries
Die Manns – Ein Jahrhundertroman, which told the life and work of German writer
Thomas Mann, played by
Armin Mueller-Stahl. He played Franz Westermeier who inspired Thomas Mann to write
Confessions of Felix Krull. Still in 2001, he also discovered his passion for Brazilian cinema and the Portuguese language through a special at the
Berlin International Film Festival. He began to master the language and expanded his range to South America.
Cinema, Aspirins and Vultures, by
Marcelo Gomes, premiered in 2005 at the
Cannes Film Festival. The critically acclaimed film won several national and international awards and was distributed in Germany by Arte Television. The film also represented Brazil in the dispute for the
Academy Awards for the best foreign film, but was not nominated. He played Johann Hohenfels, a fictional character who flees the chaos of WWII and as a peace-loving pacifist travels the backlands of Brazil selling Aspirins to the poor by showing them commercial films through his movie projector, completely new for them at the time. From 2004 to 2006, he took turns in German and Brazilian productions: he was part of the main cast of the new prime time series
Die Gerichtsmedizinerin. In 2005, he played Mark, a German tourist who gets involved in an unhappy relationship with a desperate young hooker and tries life with her in Berlin, in
Deserto Feliz, a drama by
Paulo Caldas, which premiered at the Berlin Festival and won several film festivals. He was part of the cast of the soap opera
Pé na Jaca, directed by
Ricardo Waddington for
TV Globo, which was highly popular. In 2008 Ketnath worked again with
Joseph Vilsmaier, participating in the main cast of the film '''', based on a book by
Wolfgang Franz von Kobell. The film was a box office success and became a modern classic that is often repeated on German TV. The year 2009 saw the beginning of his work in the criminal series
Stuttgart Homicide, playing the lead male detective who sticks to his personal freedom and his own sense of justice. The series is popular and in 2021 has entered its 13th season. In 2014, he participated in the Brazilian comedy
Os Homens São de Marte... E é pra Lá que Eu Vou!. The romantic comedy was the most watched national film in Brazil in 2014. In the Brazilian animation
Nimuendajú, directed by Tania Anaya, he played the ethnologist
Curt Nimuendajú, who lived more than 40 years with
Indigenous peoples throughout Brazil, becoming one of the most important references in studies on the subject in the 20th century. In
Klaus Mitteldorf's
Vou nadar Até Você he plays Tedesco, a visual artist who is in the midst of a mid-life crisis. When he receives a letter from a possible daughter, played by
Bruna Marquezine, life changes irreversibly for both of them. Playing a character 20 years older than himself, Ketnath proved his interpretational range another time. In 2018, he came back to the stage and participated in
Wolfgang Amadeus Mozart's opera
Die Entführung aus dem Serail in the role of Bassa Selim, the emperor who finally frees his slave Konstanze. In 2020 the film
When in Venice premiered in several countries where Ketnath combined acting, producing and writing. His most recent work is his work on the miniseries
Passport to Freedom, directed by
Jayme Monjardim and produced by
Sony and
TV Globo. He plays the antagonist Thomas Zumckle, a general of Hitler's elite troops who falls sickly in love with
Aracy de Carvalho, a German-Brazilian secretary who saved numerous Jews from the Holocaust. == Producer ==