David Moon is a one-shot character on Frasier, and is a member of the Moon family. He is the son of Harry and Gertrude Moon, and the brother of Daphne Moon. He is briefly seen (unnamed) in "Something Borrowed, Someone Blue", when a group of Daphne's brothers move the pre-wedding party into the room Daphne and Niles are in, where the duo are discussing their feelings for each other.
The actor playing the role is not identified on IMDb.