Often the most memorable TV show characters are those the audience never gets to eyeball. Mrs. Wolowitz on The Big Bang Theory comes to mind. If the face behind Howard's loud 'roommate' was ever revealed, their shouting matches wouldn't be as funny.
Carlton the Doorman/Rhoda (CBS) 1974-78
While the face of the drunken doorman Carlton (Lorenzo Music) was never seen on this The Mary Tyler Moore Show spinoff, his voice is familiar to Garfield fans. Known for his notorious intercom rants (the thing of legend) Carlton did appear once wearing a gorilla mask, which allowed for this recurring favorite to make our list.