I’m not claiming a "superstar’ for this one, but I recently realized there is only one actor where I have seen all shows from three different series.
Annie Potts was/is in:
Dangerous Minds - only one season so it doesn’t fit the OP.
Designing Women
Young Sheldon
It seems to me that to be a ‘primetime superstar’ it’s really not enough to just have been on a show for a long time. No one would think Mariska Hargitay or Mark Harmon is a ‘superstar’. Tyoically, when I think of TV superstars, the list looks like this:
Dick Van Dyke
Mary Tyler Moore
Lucille Ball
Carol Burnett
Betty White
Tom Selleck
Andy Griffith
Bob Newhart
Jerry Seinfeld
Alan Alda
None of them are in the running for most TV appearances, but all of them rose to the pinnacle of TV stardom and stayed there for a long time.
While not technically a TV series, I think that we might also include the long-running series of television ads which Garner did with Mariette Hartley for Polaroid instant cameras – Wikipeida says that they did 250 commercials over 8 years (1978-85). The ads were very popular, and led many viewers to believe that Garner and Hartley were a couple in real life.
An example: https://www.youtube.com/watch?v=pt82z_GUCKw
Katherine Helmond gets in for Soap and Who’s the Boss, plus her being injected into the last two seasons of Coach.
Shelley Fabares has Coach, The Donna Reed Show, and a juicy role as the nemesis in One Day at a Time.
Howard Hesseman ended up married to Ann Romano in One Day at a Time, along with starring in WKRP in Cincinnati and Head of the Class.
And in one of those “only in Hollywood” type of things, Valerie Harper managed to get fired from her own show, which nevertheless went on for four more seasons without her. Oh yeah, she was also in Mary Tyler Moore and Rhoda.
Speaking of Mariette Hartley (whom I always liked), she’s had quite a productive show business career herself—very active in TV and film from 1958 to 2022. Hard to believe she’s now 82.
I’m not sure who the superstar is yet, but The MTM Show has a remarkable number of main cast members who did a lot of seasons and episodes of successful programs (MTM herself, Ted Knight, Ed Asner, Gavin McLeod, Valerie Harper, Betty White)
Bill Bixby gets in for My Favorite Martian, The Courtship of Eddie’s Father, and The Incredible Hulk.
Technically Robert Urich doesn’t qualify, having only two long-running shows. But he deserves some mention for having a lead role in (by my count) TEN different series that lasted one season or less.
Charlie Sheen racks up a pretty good episode count for Spin City, Two and a Half Men, and Anger Management.
I know that technically, Anger Management ran only two seasons, but the second season had ninety freakin’ episodes, for syndication reasons, giving the series a grand total of a hundred. I mean, that’s the equivalent of at least four normal seasons, if not more.
Since Sam_Stone mentioned Bob Newhart:
A rare instance where someone had two shows named after themselves that both were successful.
To be fair, Bill Cosby had a sitcom named after himself before The Cosby Show and it ran 50+ episodes.
And then, he had a third one that ran almost 100 episodes that was probably his second most popular TV thing.
Plus:
I’d call Bob and George & Leo misfires, not successes, though.
I ask for a ruling on John Forsythe. In addition to his long-running roles on Dynasty and Bachelor Father, he was also the uncredited but easily recognized voice of Charlie in 108 episodes of Charlie’s Angels.
I’ll allow it
How about H. Jon Benjamin
Bob’s Burgers - 255 episodes
Archer - 135 episodes
Dr. Katz, Professional Therapist - 81 episodes
Aren’t all of those animated shows? The OP limited the discussion to live-action shows.
Oh, sorry, I missed that.
Still, I think it’s an interesting adjunct to the discussion. There are lots of actors with two successful series, but it’s hard to find those with three. That’s true of voice actors as well as live-action.
Jackie Gleason
If you don’t count his variety shows (though they were prime time and included scripted comedy sketches), Gleason may not fit all the criteria, but he was certainly a TV superstar/legend. He was also a fine movie actor (e.g. The Hustler).
Life of Riley – 26 eps
The Honeymooners – 39 eps
The Jackie Gleason Show (1952-58) – 161 eps
The Jackie Gleason Show (1966-70) – 40 eps
He was also a fine pool player. He was recommended for the role by Minnesota Fats, a player who was roughly the prototype for Gleason’s character, because Gleason could already play very well. He had a history as a pool hustler.
Paul Newman, on the other hand, had never played a game of pool in his life before being cast. He had a pool table set up in his dining room and practiced constantly for weeks under the tutelage of Willie Mosconi, the best straight pool player ever. By the time they shot the movie, Newman had become a pretty good player.