Here are 5 celebs that did not appear on Maude yet should have and could have, at least in the sense that they were active in the series' 1972-1978 run.
1) Richard Nixon: Talk about an icon! OK, he may have been a little busy during the Seventies, but this Lear sitcom would have made a nice follow-up to capitalize on the career momentum he squandered after his comedy acting debut on Laugh-In.
2) Marjoe Gortner: Fresh off exposing the business of evangelism (his part of it, anyway) in 1972 documentary Marjoe, he could have played a man of the cloth tangling with our heroine. We're lucky to have his appearances in the likes of Medical Center and Pray for the Wildcats, but seeing him and Bea Arthur today would have been a treat.
3) Katharine Hepburn: Something about Hepburn doing this sitcom, let alone her acting alongside Arthur, makes me smile. Maybe she could be a stuffy teacher of Phillip (remember him?) who Grandma Maude crosses swords with, or a stuffy community leader Maude tangles with or a stuffy--well, some kind of stuffy patrician that lets Maude show off her "salt of the earth" credentials.
4) Anita Bryant: One of the series' later episodes does feature several references to Bryant's famous anti-gay-rights campaigning of the 1970s, but she wasn't actually on the show. Imagine her and Maude arguing about--eh, you know, actually that might not be a fun watch after all.
5) Sammy Davis Jr.: All it took was one listen to this to make me want to see this happen:
We know Sammy loved TV. We know Maude loved to do "put on a show" shows. Why not combine these factors and have Davis as the celeb get for a big benefit, climaxing in his singing the show's theme song (the characters wouldn't know it was the theme song) TO Maude. Just a few minutes of him scatting, "Maude, Maude, Maude," right to Bea Arthur would make it worthwhile.