Mary Tyler Moore played a pair of legs on Richard Diamond, Private Detective (1959). Her character, Sam the answering service girl, was only seen from the waist down.
Norm’s wife actually appeared on the Thanksgiving feast at Carla’s house. She was only shown from the rear until she got a faceful of mashed potatoes in the food fight.
Corrections
[ul]
[li]Binnie, Nina’s drinking buddy, on “Just Shoot Me”, has appeared once, in episode The Mask[/li][li]Robin Masters was played by Orson Welles on “Magnum, P.I.” from 1981 to 1985.[/li][li]One I thought of, but dismissed: Dr. Selar on “Star Trek: The Next Generation”. She was played by Suzie Plakson in one episode, “The Schizoid Man”.[/li][/ul]
I thought Welles had appeared on-screen as Robin Masters. But according to an episode guide, he was only the voice. However, Magnum once mentioned that Masters looked like Orson Welles.
George Steinbrenner on “Seinfeld” (you only saw the back of his head).
Mammy Two-Shoes from the old “Tom and Jerry” cartoons. You only saw her feet. Okay, so it’s not a TV show, but I saw it on TV.
Sparky, the radio operator friend of Radar, on “MAS*H.”
Guy Propski:
For some reason, Sparky did appear briefly in one episode. IIRC, he was a slim guy (w/ glasses), with a ‘farm-country’ accent. He was reading a comic book when Radar called him (perhaps Radar had sent him the comic book, I don’t remember).