And Then There Were None (1945)
Rene Clair's 1945 Agatha Christie adaptation. The template for every isolation murder mystery since.
Actor: Barry Fitzgerald
Barry Fitzgerald was nominated for both Best Actor and Best Supporting Actor for the same performance in Going My Way, which the Academy changed the rules to prevent afterward. He won the supporting award. He came from the Abbey Theatre in Dublin and worked with John Ford repeatedly, including The Quiet Man.