Obviously Bob Newhart's two iconic shows are enough for one actor, but he also had a very good guest role on NCIS a few years ago, playing the medical examiner's predecessor, then suffering from Alzheimer's. In the last couple of years or so, NCIS did a flashback episode to around 1980, when Newhart's character would still have been on the job and not suffering from Alzheimer's at that time. Because Newhart was so great previously in the role as the older version of the character, NCIS' casting people for this episode had to find someone to play the middle aged version of the character who sort of looks like Newhart, but more importantly sounded like him.
I haven't watched any of the series that Carol Burnett is in where she is apparently in a coma most of the time. It also stars Kristen Wiig, who I've always thought of as the only actress that could possibly do the type and range of stuff that Carol Burnett did. I hope the series has some scenes with them together where Carol Burnett is at least awake. Those two could be a riot together.