Harry Baer began his career in Munich when he joined the Action Theatre, a theatrical experimental group that later regrouped as the Antitheather under the leadership of Rainer Werner Fassbinder.
He had starring roles in Gods of the Plague (Götter der Pest) (1970) and Jail Bait [de] (Wildwechsel) (1972), both directed by Fassbinder.
On the night of Fassbinder's death, Baer was the last person with whom he spoke before his body was found.
Das atemlose Leben des Rainer Werner Fassbinder) Kiepenheuer & Witsch, Köln 1990, ISBN 3-462-02055-2.
After Fassbinder's death Baer acted in movies by Mika Kaurismäki, Werner Schroeter, Jeanine Meerapfel, Bernhard Sinkel and Doris Dörrie among others.