The name of Rhoda's frequently heard but almost never seen doorman on the 1974-1978 U.S. TV sitcom "Rhoda" is Carlton, played by Lorenzo Music. In this CBS series, he is the drunken doorman to the building where the main star, Rhoda Morgenstern Gerard (Valerie Harper) lives.

Carlton as the doorman in Rhoda's building is often heard on the intercom, but he is almost never seen. His arm occasionally appears from the front doors. In the third-season episode "H-e-e-e-r-e's Johnny", he is seen from the back after hitching a cab ride with Rhoda and her friends.

Overall Carlton is a guy who provides comic relief by having a humorous persona, scene presence, and/or witty dialogue that is often used to relieve tension among others.

More Info: en.wikipedia.org