Mary Tyler Moore’s career soared after the Dick Van Dyke Show while Van Dyke’s, because of his drinking, never really was as big again.
Rob Reiner came out of All in the Family to become a successful director. Sally Struthers – let’s just say not so successful.
Eddie Murphy vs. Joe Piscopo.
Weird Science was a nice springboard for the likes of Anthony Michael Hall, Bill Paxton, and Robert Downey Jr.
Not so for co-star Ilan Mitchell-Smith (Wyatt).
Harrison Ford had a great deal of success after Star Wars while Chewbacca found very few roles for a 7’ Wookie.
Freddie Prinze Jr and Mathew Lilliard’s ( She’s All That, Wing Commander, Scooby Doo, Summer Catch) careers appear to suck equally.
Chewbacca’s stupid ass shouldn’t have turned down Indiana Jones for yet another remake of Hamlet. Spielberg doesn’t forget.
Jane Curtin seems to have continued her career after Kate & Allie, while Susan Saint James disappeared.
Likewise, from Knight Rider, I hear David Hasselhoff is quite popular in Germany, not to mention that Baywatch thing, but when was the last time you saw KITT? 
He neede to pay the rent money, so last time I saw him, he was modeling and selling his body
Johnny Depp and Peter DeLuise enjoyed each other’s company as undercover police officers on 21 Jump Street back in the late 80s/early 90s (well, 1990). To date, Depp’s worked with an enviable list of directors, received two Best Actor Oscar nominations, and lives what by most accounts is a pretty sweet existence with his actress/singer girlfriend Vanessa Paradis and their two kids.
Peter DeLuise’s last acting role, according to the IMDB, is Vondi The German Space Tourist in a TV movie called Bloodsuckers.
David Duchovny, of X-Files fame, has enjoyed (moderate) fame post-split while Gillian Anderson’s career has been mostly dismal.
If you can count a TV show that’s still in production, Ashton Kutcher has gone on to numerous bad but very lucrative movies and silly but lucrative TV appearances and production deals, Topher Grace has at least gotten his foot in the door of big budget comedies, while Wilmer Valderrama is still lisping with an accent the increasingly unfunny and pathetic exchange student Fez.
Taxi is an odd case in that the least attractive actor (Danny Devito) became by leaps and bounds the richest and most successful and powerful actor from the ensemble, Judd Hirsch and Tony Danza and Marilu Henner all had successful careers in television, and Andy Kaufmann became (for whatever reason) an icon, but poor Jeff Conaway just sort of stayed behind in Has Been land. (He appeared on the Child Star video in Dickie Roberts (the movie is an abomination but the video is worth renting the DVD], which was inexplicable as he was never a child star.)
Roseanne (formerly Barr) is richer than most archduchesses I’m sure, but since her show folded she has gone from one disaster to another professionally while John Goodman (even though his post Roseanne sitcoms have flopped) has had a very successful career as a character actor and SNL staple.
Actually, there were three kids, the third being the older brother. Imagine being eclipsed by Henry Thomas!
Lenny/Michael McKean is all over movies and television, but Squiggy/??? is not.
I thought Dick had a successful show in the 80’s-90’s as some sort of detective(I’m too lazy to IMDB him).
In fact I’m sure it ran more years than MTM’s show.
OK I’m going to IMDB this…
I was right.
Dick Van Dyke’s Diagnosis Murder ran for 8 years - more than MTM’s acclaimed show.
Don’t forget Christopher Loyd aka Reverend Jim Ignatowski, who scored a good gig in those “Back to the Future” movies.
That’s largely because Dawber intentionally stepped away from her acting career in the main in order to raise her family. She and Mark Harmon (Navy NCIS) have two children and helped raise Mark’s nephew.
Susan Saint James likewise chose family over working regularly in TV and movies after Kate & Allie. She’s married to Dick Ebersol, an executive for NBC. You may recall that Ebersol and the couple’s two sons were in a plane crash a few months ago, and the younger son was killed.
David Lander, who played Squiggy on Laverne & Shirley has multiple sclerosis. While the disease has progressed slowly, he has focused on his health rather than his career.
Peter’s been directing the Star Gate series on SCIFI. 
He was in Babylon 5. That count for anything?
True, but DVD had a successful Broadway and movie career before his drinking got out of hand. While I don’t mean to say he starved, his career went downhill while MTM soared.
Yeah, it was weird to run into him at college, I had a few classes with him. He was always on roller blades.
Ooh! Ooh! I kow this one! Burt Ward is now running Boy Wonder Visual Effects. They did the special effects for Bulletproof Monk and a couple other movies. (Thanks, VH1)