The Last Man on Earth (1924)

In the future year of 1940, a young man is rejected and humiliated by a girl and goes off to be a hermit in a redwood forest. By 1950, a dreadful plague of "Masculitis" has killed every male over the age of puberty but our hermit hero. He's become a national treasure, and millions of man-starved females crave him, yet he still wants the gal who wouldn't have him.