Dr. Jekyll and Mr. Hyde (1941)

In the 1941 movie "Dr. Jekyll and Mr. Hyde," based on the classic novella by Robert Louis Stevenson, Dr. Jekyll conducts experiments and creates a potion that unleashes his dark alter ego, Mr. Hyde. As Dr. Jekyll transforms into Mr. Hyde, he becomes increasingly consumed by his violent and immoral tendencies. The film explores the duality of human nature and the consequences of giving in to one's darker impulses.