All in the Family - “Those Were the Days” sung by Carrol O’Connor and Jean Stapleton.
Green Acres - sung by Eddie Albert and Eva Gabor.
The Monkees - “Hey, Hey, We’re the Monkees,” recorded by session musicians, but Micky Dolenz did sing the lead.
Family Guy - sung by Seth MacFarlane, Alex Borstein, Seth Green, and Mila Kunis.
Any other examples of theme songs sung by the main cast members?
The Brady Bunch theme song was performed by the kids in the cast in seasons 2-5.
Lee Majors-The Fall Guy (The Unknown Stuntman)
Mercifully, I’ve erased the memory of Lee Majors’ “singing” from my memory. He was absolutely awful in the “Six Million Dollar Man” episode that introduced Jaime Sommers as the Bionic Woman.
Merle Haggard was the narrator on Dukes of Hazzard and sang the theme.
I thought that was Waylon Jennings.
Also, although it was only done once, the leads of “Bonanza” sang the show’s title song (which is usually heard only as an instrumental).
NDP is correct. The cast of Bonanza rode off into the sunset at the end of the final episode, singing the theme song.
I’m pretty sure that Kelsey Grammer sang the opening ditty (something about scrambled eggs?) for Frasier.
On the ABC sitcom The Neighbors, I think the actor playing Larry Bird sings the theme song.
I think that was the closing ditty.
Doris Day sang “Que Sera, Sera” for The Doris Day Show.
Dean Martin sang “Everybody Loves Somebody” as the theme for The Dean Martin Show.
The Fresh Prince of Bel-Air.
Craig Ferguson sings the late late show theme
He sang three or four variations of the closing ditty. I believe he wrote the lyrics as well, but was forbidden from mentioning any of the show’s elements, which is why “tossed salad and scrambled eggs” came about instead.
That was actually the pilot episode. NBC deemed the sequence to be too campy and removed it before the episode aired.
“Bonanza” theme - sung by the Cartwrights
Peter Davison sang the opening theme to his period detective series Campion–which had no lyrics, but just went “La la la, la la-la…”
New Tricks, a British cold case cop show that you can see on some PBS channels, has a theme song that is sung by Dennis Waterman, one of the original four stars and the only one of the original that is still on the show (as of 2013 I think).