The Unearthly (1957)

Professor Charles Conway is a mad scientist attempting to develop the proverbial fountain of youth by creating "the 17th gland". Ignoring all aspects of scientific ethics, his research subjects are people who have no family and are under the impression that the doctor can cure their depression. However, his research hasn't been successful and his subjects are turned into grotesque zombies. Some of Conway's patients begin to catch on to his scheme and intend to stop him.