Depending on how you want to view it, all of the incarnations of The Doctor are alive (or all dead).
Threads go where they go but…
I really didn’t want this to be about immortals. I wanted to read whether you all thought Richard Kimbal was still alive. 
In a related series, I don’t think Paul Bryan survived much past the 3 year run for his life. The chances he’s still alive are pretty much nil. An effective treatment for his condition didn’t happen until 2001.
Illya Kuryakin. Retired and enjoying the good life.
Working part time in a Navy Morgue.
Jimmy Olsen and, much to my surprise, Lois Lane* are still kicking it around old-school Metropolis, which used to look like Los Angeles for some reason.
- Phyllis Coates edition.
Morphed into John Malkovich’s character in R.E.D.s
YES!
In Russia, or moved to NYC? I picture him in a cute little dacha on a lake somewhere.
Gabe Kotter may still be around telling bad jokes at the retirement home.
His remedial history class students are all still around, just now nearing retirement
What? Who?
ooohooooh Missta Kottah I know!
Julie left Gabe back in 1990 and never remarried.
Barbarino became an actor. he had a string of roles in off- and off-off Broadway, but his theater career never took off. he ended up working 20 years on The Young and the Restless.
Horshack went to community college and took a string of medium grade jobs until the internet came out. He found his calling doing podcasts, and is the host of a successful true crime podcast.
Freddie Washington tried to be a disc jockey but could not find work. He went to college and became a teacher. He taught (non-remedial) science in a Brooklyn high school until retirement last year. He became a local celebrity when, as a teacher, he took a baseball bat to the head of a drug dealer threatening a female student.
Epstein joined the Army out of High School, where he served four years. He came back to NY and married a nice Puerto Rican Jewish girl and they had 7 kids. He worked as a mechanic for a Brooklyn Chevy dealer. Yes, Epstein became Mr Goodwrench.
Dexter Morgan died in a workplace accident not long after the series finale after he faked his death and assumed a new identity as a lumberjack.
Dennis The Menace: Dennis got drafted, went to Viet Nam, then came back to run a chain of RV dealerships. Margaret and Joey got involved in a Dom/Sub relationship and eventually got married. Dennis died of a heart attack back in '06, but Margaret and Joey are still alive and retired to a ranch in Montana.
Timmy and Jeff are still alive, but alas, Lassie passed away.
I would submit that she did remarry. She relocated to Cincinnatti and met Bailey, now head of the news department, and they’re very happy.
NO! Bailey was waiting for me!
Les never married. He lived in that small apartment until he had to be moved to a managed care facility. He died of cancer. He always voted republican because he thought they were the best party to stop communism.
Herb had a heart attack at 59. Lucille never remarried, but moved to Florida.
Gordon Simms, aka Venus, stayed a disc jockey for another decade until the market declined. he eventually went into station management and ran a station in San Diego until he retired. Lifelong Democrat.
Johnny Caravella, aka Johnny Duke, Johnny Style, Johnny Cool, Johnny Midnight, Heavy Early and Dr Johnny Fever jumped around markets all over the country, and eventually landed his own channel on Sirius XM. Never voted. Doesn’t trust the government.
Jamie Farr, who played Klinger, was born in 1934. Not only is he old enough to actually be a corporal in Korea, he’s still alive.
Strangely enough, both Alexander Bumstead from the 1950s Dagwood TV series and young Donnie Henderson from the TV version of Beulah are still alive.
All the regular adults from both are all deceased, including the 3 Beulahs.
Speaking of Richard Crenna. All the main male Real McCoys are gone but the two main female McCoys, Kate and Tallahassee/Hassie, are still going. Farm life is easier for women than men, I guess.
Oliver Wendel slipped and fell in the pig sty and couldn’t get up, breaking his hip. After two days of calling out for help, Arnold Ziffel began munching on all his soft spots. He was found dead a week later by Eb. The reason Lisa didn’t come to his rescue was because years earlier she got sick of his shit and moved back to the city with Mr. Haney.
The satirical Viz magazine did an Onion style news article about 2 of the characters in The Good Life a while ago. It reported that Margo Leadbetter had died of cancer at home in Surbiton, at the age of something like 63. She was survived by her husband Jerry Leadbetter.
Part of the joke was the fact that Penelope Keith, who played Margo, was and is still alive, while Paul Eddington, who played Jerry, had died a few years previously.