Oscar Homolka (born August 12, 1898 in Vienna, Austria, died January 27, 1978 in Sussex, England) was an Austrian-American actor.

Homolka attended the Royal Dramatic Academy in Vienna and began his career on the Austrian stage. Success there led to work in the much more prestigious German theatrical community in Munich and Berlin. His first films were Die Abenteuer eines Zehnmarkscheins (The Adventures of a Ten Mark Note, 1926), Hokuspokus (Hocuspocus, 1930), and Dreyfus (The Dreyfus Case, 1930). After the Nazi rise to power, Homolka moved to Britain in 1934 and later was one of many Jewish actors and theatrical people who fled Europe for the United States.

In 1936, he played the bomber in Alfred Hitchcock's Sabotage. Although he often played villains such as Communist spies and Soviet-bloc military officers or scientists, he was nominated for an Oscar for his portrayal of the crusty, beloved uncle in I Remember Mama (1948). Homolka also acted with Ingrid Bergman in Rage in Heaven, with Marilyn Monroe in The Seven Year Itch, with Ronald Reagan in Prisoner of War, and with Katharine Hepburn in The Madwoman of Chaillot.

Homolka returned to England in the mid-1960s, to play the Soviet KGB Colonel Stok in Funeral in Berlin (1967) and Billion Dollar Brain (1968), opposite Michael Caine. His last film was the Blake Edwards romantic drama The Tamarind Seed in 1974.