Werner Klemperer, known forever as Colonel Klink in Hogan's Heroes, refused that role until the producers agreed to rewrite it so that he was a bumbling fool who never succeeded at anything. He once said, "I had one qualification when I took the job: if they ever wrote a segment whereby Colonel Klink would come out the hero, I would leave the show." His father was Jewish, and his family left Germany in 1935 before it was too late.
Conrad Veidt was a very popular German actor in the 1920s to early 30s. In 1933, Goebbels was purging all Jewish actors from film & stage. Veidt had just re-married, to a Hungarian Jew. He was told by Goebbels' minions that if he divorced her and declared support for the Nazi regime, he could continue acting. His reaction was to fill in the "Race?" question with "Jude" in the questionnaire sent to all actors, though he himself wasn't Jewish, but rather was demonstrating his solidarity with his wife (like the non-Jewish Danes who put on the yellow star). Immediately after, they emigrated to the UK before Goebbels could arrest them.
After 8 years of starring in anti-Nazi movies, he & his wife moved to Hollywood for the express purpose of making movies that would help convince Americans to support the British war effort. Similar to Klemperer, he had his contract mandate that he would only play German characters if they were villains.
BTW, Hogan's Heroes Trivia: The actor who played Corporal LeBeau is a French Jew who spent 3 years in Buchenwald, and still has the tattoo on his arm today. 12 other family members went to Auschwitz and none came back. The only thing that saved him was his ability at the age of 16 to sing & dance and entertain the SS soldiers at the camp.
Also, Leon Askin (General Burkhalter)
Askin was born into a Jewish family in Vienna, the son of Malvine (Susman) and Samuel Aschkenazy. According to his autobiography his first experience of show business occurred during World War I when he recited a poem before Emperor Franz Joseph. In the 1920s, he studied acting with Louise Dumont and Max Reinhardt. While working at Vienna’s “ABC” cabaret theater in the 1930s, he frequently directed the works of dissident political writer Jura Soyfer.
Askin immigrated to the United States in 1940 and, served in World War II as a Staff Sergeant in the US Army Air Forces.
Lived to the ripe old age of 97.