Yesterday’s Mystery Person was Conrad Veidt.
From Wikipedia: Veidt was a German-born British actor. He attracted early attention for his roles in the films Different from the Others (1919), The Cabinet of Dr. Caligari (1920), and The Man Who Laughs (1928). After a successful career in German silent films, where he was one of the best-paid stars of UFA, Veidt and his new Jewish wife Ilona Prager left Germany in 1933 after the Nazis came to power.