Henry Koster
A whimsical man is thought to be insane due to his insistence that he is best friends with an invisible, humanoid rabbit, but he may be wiser than anyone knows.
The classic stage hit gets the Hollywood treatment in the story of Elwood P. Dowd who makes friends with a spirit taking the form of a human-sized rabbit named Harvey that only he sees (and a few privileged others on occasion also.) After his sister tries to commit him to a mental institution, a comedy of errors ensues. Elwood and Harvey become the catalysts for a family mending its wounds and for romance blossoming in unexpected places.