I've been fascinated by which classic TV series still have surviving cast members and for how long, mostly spurred on by the fact that so many actors have departed of late.

I mean ... the entire main cast of Laverne & Shirley (January 27, 1976-1983) is gone except for Michael McKean (b. October 17, 1947) is gone and that, due to my age, feels like a relatively recent series. (Oops, it's coming up on 50 years old.)
I have known (or thought?) for some time that the oldest series with its entire MAIN cast still living is My Brother the Angel aka The Smothers Brothers Show (September 17, 1965-1966), reason being that Tommy (b. February 2, 1937) and Dick (b. November 20, 1938) Smothers were the only regulars. Please Don't Eat the Daisies (September 14, 1965-1967) had been the record-holder until Kim Tyler (1954-2021) died, before either of the show's parents.
Another show with incredible longevity among its stars would be The Love Boat (May 5, 1977-1987), which had a living main cast for 44 years, until the death of Gavin MacLeod (1931-2021).
These observations made me reflect on just how many early-TV survivors are out there. To be sure, any list of celebrities 80 and older would contain a large number of actors who appeared on early filmed plays, or who made guest appearances on '50s shows, or who, of course, appeared on early talk and variety shows; there are, thankfully, too many to even summarize still.
But I thought I would do a deep dive into just how many Golden Age of TV actors who were regulars on shows are still with us. For my purposes, I stuck to shows that debuted in 1959 or earlier (the Golden Age of TV is generally thought to be from 1947-1960). I was mostly interested in regulars, but I also included actors who recurred, as long as they played the same character.
Even with all these stipulations — check out all the surviving TV veterans I found! And this is a living document, so PLEASE tell me who I'm forgetting.

Captain Video and His Video Rangers (June 27, 1949-1955) & The Secret Files of Captain Video (1953-1955): These nightly sci-fi series logged 122 episodes and 14 episodes, respectively. Don Hastings (b. April 1, 1934) appeared in 114/122 and 11/14. Hastings, a TV veteran, is still around and still granting interviews.

Mama (July 1, 1949-1957): Robin Morgan (b. January 29, 1942), who played Dagmar on 153 of 176 episodes — making her a legitimate regular cast member — is still with us at 81, and is a famous feminist activist. Patty McCormack (b. August 21, 1945), who was Ingeborg on 13/176 episodes and therefore was recurring, is with us at 82. Joyce Van Patten (Dick's sister, a fine actress in her own right, b. March 9, 1934), made a trio of appearances.
The Magic Cottage (July 18, 1949-1955): An NYC-based children's series whose Don Hastings (b. April 1, 1934) appeared on 55/61 shows.

The Aldrich Family (October 2, 1949-1953): Though a radio program forever, and a series of movies, only 19 TV episodes were made, so Robert Casey (b. June 27, 1927), who played Henry on 6/19, almost qualifies as a main cast member. Richard Tyler (b. September 23, 1932), who played Henry later on 6 episodes is also with us.
Man Against Crime (October 7, 1949-1954): This series was a one-man show, the man being Ralph Bellamy (1904-1991), who was on all 125 episodes. But interestingly, actress Nita Talbot (b. August 8, 1930) played a character called Gloria on 9/125 episodes, making her the next most often-credited player.

Your Show of Shows (February 25, 1950-1954): Regular Carl Reiner died in 2020 at 98. Bill Hayes (b. June 5, 1925), who appeared on 17/139 episodes (1950-1953), and Bambi Linn (b. April 26, 1926), who appeared on 9/139 episodes (1952-1954) are the last surviving recurring cast members, and are among the oldest living veterans of early TV.

Dick Tracy (September 11, 1950-1952): This TV version of the iconic comic strip has one survivor: Margia Dean (b. April 7, 1922), who played Officer Mary Faelb on 6/48 episodes. Note: The actress who played Breathless Mahoney, Jo-Carroll Dennison, lived to be 97, dying in 2021.
You Bet Your Life (October 4, 1950-1961): Of course, Groucho (1890-1977) is long gone, but a Marx is alive who appeared on 7/211 episodes: his daughter Melinda (b. August 14, 1946).

Search for Tomorrow (September 3, 1951-1986): Look, soaps have a LOT of episodes (this one had 5,138) and there are a LOT of people who have been on soaps, so I'm keeping my list of living members tight. Luckily, an original cast member of this 70-plus-year-old soap is still with us, Lynn Loring (b. July 14, 1944), who appeared on 240 episodes. Also, living legend Lee Grant (b. October 31, 1925) was the first Rose Peterson in 12 episodes from 1953-1954.

Love of Life (September 24, 1951-1980): One of TV's oldest soaps has a survivor in Dennis Parnell as Beanie Harper (b. January 24, 1943). He was in 34 episodes from 1952-1955, even though 32/7,387 isn't exactly a lot.

The Red Skelton Hour (September 30, 1951-1971): It's hard to find recurring anything on variety shows, but Jamie Farr (b. July 1, 1934) played the character Snorkel on 4 episodes from 1955-1956 ... out of 658 total. He was seen on 8/658, but played other characters.

I Love Lucy (October 15, 1951-1957): The main cast is gone, but not for nothin', twins Joseph A. and Michael Mayer (b. June 26, 1952), who played Little Ricky on 32/181 episodes, and Richard Keith aka Keith Thibodeaux (b. December 1, 1950), who played the same character on 24/181 episodes, are still with us. We also have Steven Kay (no b. given), who appeared on a single episode as little Stevie Appleby. From there, you'd have to hunt for one-off guests — the biggest name of which is likely Barbara Eden (b. 1931).

Adventures of Superman (September 19, 1952-1958): This show has range — its titular star died immediately after it ceased, yet it has one cast member alive over 70 years later, the great Phyllis Coates (b. January 15, 1927). Coates was the first EVER to play Lois Lane, and did so on 24 episodes from 1952-1953 out of the show's 104.

The Jackie Gleason Show (September 20, 1952-1973): Joyce Randolph (b. October 21, 1924) played Trixie on this precursor to The Honeymooners. She was on 79/167 episodes, beginning withe the Season 1 episode "Missing Pants" on December 6, 1952 — over 70 years ago.

The Adventures of Ozzie and Harriet (October 3, 1952-1966): Slim pickings, but of 436 episodes, Joe Byrne (b. March 29, 1936) was on 80, lead guitarist James Burton (b. August 21, 1939) was on 61 and Karl Kindberg aka Dink (b. June 25, 1936) was on 45.

Our Miss Brooks (October 3, 1952-1956): Recurring cast member Ricky Vera (b. February 1, 1943) was in 11/130 episodes.

The Life of Riley (January 2, 1953-1958): The son on this long-forgotten family sitcom, Wesley Morgan, turns 84 March 19. He was a regular and appeared on 190/219. His TV sis, played by Lugene Sanders, also a regular, with 140/219, will turn 89 later this year.

Make Room for Daddy/The Danny Thomas Show (September 29, 1953-1965): Regular Angela Cartwright (b. September 9, 1952) was in 222/343 as Linda Williams on this show. She's still a baby! Sherry Jackson (b. February 15, 1942) played Terry in 133/343 episodes.

Life with Father (November 22, 1953-1955): Based on a Broadway smash, it seems there are only 10 episodes known of this period-piece family series set in 1890. Many more were obviously made. Of the 10, Marion Ross (b. October 25, 1928) was in half of them, as were Harvey Grant (b. April 10, 1946) and Steven Terrell (b. December 6, 1929). Malcolm Cassell (b. March 16, 1939) was in 4/10. Eilene Janssen (b. May 25, 1938) and Freddy Ridgeway (b. February 14, 1944) were in 2/10. Yes, this series had a short run, and we aren't super sure about how many installments existed, but yes, it has a remarkable number of survivors for a 70-year-old production!

The Secret Storm (February 1, 1954-1974): Jada Rowland (b. February 23, 1943) was Amy Ames on 5,009 episodes! out of 5,229.

Lassie (September 12, 1954-1974): Stars Jon Provost (b. March 12, 1950), who joined in 1957, and June Lockhart (b. June 25, 1925), who joined in 1958, appeared on 250 and 208 episodes out of 591, respectively. Recurring players in 20+ episodes who are also still living: Joey D. Vieira (b. April 8, 1944), 91 episodes; and Todd Ferrell (b. June 1, 1948), 26 episodes; Jack De Mave (b. December 8, 1935); Larry Wilcox (b. August 8, 1947), 24 episodes.

Father Knows Best (October 3, 1954-1960): With 204 episodes, this classic has survivors in Billy Gray (b. January 13, 1938), who was in 201/204, Lauren Chapin (b. May 23, 1945), who was in 201/204 and Elinor Donahue (b. April 19, 1937), with 196/204. Only Jimmy Bates (b. February 22, 1938) logged a sizable number of episodes among remaining cast: 22/204.

The Honeymooners (October 1, 1955-1956): Yeah, the original series-proper was short ... and it wasn't even on Netflix! This one's easy — only 39 episodes, and still-with-us Joyce Randolph (b. October 21, 1924) aka Trixie was on 'em all, a rare early example of an early-TV series regular who was on every episode of their show and is still alive.
The Mickey Mouse Club (July 17, 1955-1958): By far the '50s series with the most living cast members (of course!), it seems fitting to list all the living Mouseketeers. There were 331 episodes. Appearing on all 331: Sharon Baird (b. August 16, 1942) and Bobby Burgess (b. May 19, 1941). Appearing on 330: Cubby O'Brien (b. July 14, 1946) and Darlene Gillespie (b. April 8, 1941). Tommy Cole (b. December 20, 1941) was on 290. Lonnie Burr (b. May 31, 1943) was on 235. Jay-Jay Solari (no b. given) was on 100. Don Underhill (b. September 5, 1941) was on 107. Nancy Abbate (b. June 19, 1942) was on 106. Eileen Diamond (b. June 15, 1943) was on 81. Sherry Alberoni (b. December 4, 1946) was on 73. Margene Storey (b. July 21, 1943) was on 69. Linda Hughes (no b. given) was on 52. Mary Lyn Sartori (b. January 4, 1943) and Bronson Scott (b. July 21, 1947) were on 50. Billie Jean Beanblossom (b. January 1, 1944) and Judy Harriet (b. September 13, 1942) were on 42. Mary Espinosa (no b. given) was on 39. John Lee Johann (b. December 23, 1942) was on 29. Ronnie Steiner (b. November 21, 1942) was on 26. Dallas Johann (b. June 14, 1944) was on 11.
So, a total of 21 Mouseketeers are alive out of 39.

Joe and Mabel (September 20, 1955-1956): Nita Talbot (mentioned even earlier) played Mabel Spooner, so is a very early main cast member. She was on 4/4 known episodes of this one.

The Life and Legend of Wyatt Earp (September 6, 1955-1961): Mason Alan Dinehart (b. April 30, 1936) turns 87 in April, and he played an important recurring role (39/226), as Bat Masterson.

Gunsmoke (September 10, 1955-1975): One of the granddaddies of early TV, the eternal series was once the longest-running of all time. Buck Taylor (b. May 13, 1938) played Newly on 174 of 635 episodes.

It's Always Jan (September 10, 1955-1956): Janis Paige (b. September 16, 1922) — she's 100 and with us — starred as a widowed singer on this short-lived show. Its titular star, she was in 26/26 episodes. Jeri Lou James (August 26, 1945) was on 11/26.

Fury (October 15, 1955-1960): The titular star was a horse, of course, but former kid actor Roger Mobley (b. January 16, 1949) scored 38/116 episodes. Jimmy Baird (b. November 5, 1945) had 36/116. And movie star Ann Robinson (b. May 25, 1929) had 9/116.

As the World Turns (April 2, 1956-2010): Rosemary Prinz (b. January 4, 1931) was Penny Hughes on hundreds episodes of this iconic (7,996 episodes) soap, but exact numbers are nearly impossible to know for soaps — too many episodes are utterly gone.
The Edge of Night (April 2, 1956-1984): I'm not sure, but I believe the only original cast member of this iconic series who's still living is (and he's mentioned in two other places on this list) Don Hastings (b. April 1, 1934). IMDb lists him on 5/6,651 episodes, but it is probably impossible to know on how many he actually appeared, just that he did.

Stanley (September 24, 1956-1957): Buddy Hackett (1924-2003) starred as a newsstand cashier in a high-end NYC hotel in this short-lived sitcom. His girlfriend on the show went on to become a TV legend: Carol Burnett (b. April 26, 1933); she was on 14/19 episodes. Interestingly, Woody Allen (b. 1935) played a writer on 2/19 episodes.

The Gale Storm Show: Oh! Susanna (September 29, 1956-1960): Of 126 episodes, Nancy Millard appeared on just 4 — but having just turned 94, she's a survivor.

Doctor Christian (October 1, 1956-1956): Soap legend Macdonald Carey (1913-1994) was the titular star, but give it up for Nurse Betty aka Jan Shepard (b. March 19, 1928), who was featured on 6/40 episodes.

Tales of Wells Fargo (March 18, 1957-1962): This western ran for 201 episodes. Lory Patrick (b. April 8, 1938) appeared on 15. Mary Jane Saunders (October 12, 1943) was on 13.

Leave It to Beaver (April 23, 1957-1963): Jerry Mathers (b. June 2, 1948) aka The Beav is the show's final living rep among its main cast. He appeared on all 235 episodes, and also reprised the role on a future sequel series. Robert "Rusty" Stevens (b. November 25, 1948) was on 68/235. Stanley Talbot (b. February 28, 1949) was on 57/235, Richard Correll (b. May 14, 1948) was on 32/235, Jeri Weil (b. May 15, 1948) was on 31/235, Tiger Fafara (b. January 3, 1945) was on 18/235 and Buddy Joe Hooker (b. May 30, 1942) was on 15/235.

Richard Diamond, Private Detective (July 1, 1957-1960): This P.I. show featured Barbara Bain (b. September 13, 1931) on 5/77 episodes.

Have Gun — Will Travel (September 14, 1957-1963): This western, focused on gunslinger Paladin, has a couple of survivors. One is Lisa Lu (b. January 19, 1927), who played a Chinese girl known only as (wait for it) Hey Girl. She appeared on 21/225 episodes, but was actually one of the Top 5 most-recurring characters. Edward Faulkner (b. February 29, 1932), a guard, appeared on 13 episodes.

Bachelor Father (September 15, 1957-1962): Sue Ane Langdon (b. March 8, 1936) is the only recurring I could find, with 16/157 episodes on this sitcom — the only show to ever run on ABC, CBS and NBC.

Sugarfoot (September 17, 1957-1961): Sugarfoot is one of the oldest series whose undisputed star is still alive — Will Hutchins (b. May 5, 1930), the titular star, appeared on all 69 episodes.
No other actor appeared on more than a handful of episodes, though Michael Dante (b. September 2, 1931) logged 3/69.

Wagon Train (September 18, 1957-1965): The long-running western boasts two noteworthy survivors: Robert Fuller (b. July 29, 1933), who was on 60/284 episodes and Michael Burns (b. December 30, 1947), who was on 54/284 episodes. A rare series with no cast members who appeared on every episode.

The Real McCoys (October 3, 1957-1963): Yeah, so, there were a lot of westerns! From this one, main cast member Kathleen Nolan (b. September 27, 1933) scored 185/225 episodes. Lydia Reed (b. August 23, 1944) was in 124/225. Of note, Butch Patrick (b. August 2, 1953) aka Eddie Munster was Greg Howard on 7/225.

How to Marry a Millionaire (October 7, 1957-1959) Based on the movie of the same name, this frothy series had a total of 52 episodes. Appearing on all 52 was Barbara Eden (b. August 23, 1931), as Loco Jones.

Zorro (October 10, 1957-1959): The sword-slinging was fast and furious, and only a couple of actors who recurred still ... recur: Jolene Brand (b. July 31, 1934) had 9/82 and Suzanne Lloyd (b. November 11, 1934), who had 7/82 (at least one of which was as a different character from the others).

The Donna Reed Show (September 24, 1958-1966): From this wholesome sitcom, we have former child actor and now child-actor advocate Paul Petersen (b. September 23, 1945), who was on all 275 episodes and Shelley Fabares (b. January 19, 1944), who was on 191/275. There's also Patty Petersen (b. December 2, 1944), who was on 99, Ann McCrea (b. February 25, 1931), who was on 73/275 and Jimmy Hawkins (b. November 13, 1941), who was on just 20/275.

77 Sunset Strip (October 10, 1958-1964): This hip series has main cast member Jacqueline Beer (b. October 14, 1932) with 149/206 and recurring Robert Logan (b. May 29, 1941) with 72/206.
Rawhide (January 9, 1959-1965): The most famous living actor who has roots in 1950s TV would be this show's Clint Eastwood (b. May 31, 1930); he was in all 217 episodes.

Laramie (September 15, 1959-1963): Robert Fuller (b. July 29, 1933) — mentioned twice here — was the series lead, and was in all 124 episodes. Dennis Holmes (b. October 3, 1950) was in 50/124. Robert Crawford Jr. (b. May 13, 1944) was in 34.

The Many Loves of Dobie Gillis (September 29, 1959-1963): Sadly, titular star Dwayne Hickman died in 2022. But we have Zelda herself, Sheila James Kuehl (b. February 9, 1941) is not only still alive, she's in Congress. She was in just 33/148 episodes, in spite of being closely associated with the series. Future movie star Tuesday Weld (b. August 27, 1943) was on 19/148. A number of others had shorter runs — including Warren Beatty (b. March 30, 1937) with 5/148 — but it seems worth noting that Hickman's movie-actor brother Darryl Hickman (b. July 28, 1931) was also on 3/148 as Davey Gillis.

Hotel de Paree (October 2, 1959-1960): Series lead Earl Holliman (September 11, 1928) is about to hit 95, and was in all 32 episodes of this western about a gunslinger who is made sheriff of a town after blowing away a bad guy.

Dennis the Menace (October 4, 1959-1963): Now we're getting somewhere! We just missed long-lived Gloria Henry (who died at 98 in 2021), but survivors are titular lead Jay North (b. August 3, 1951), who was in all 146 episodes, plus Jeannie Russell (b. October 22, 1950) who, in spite of only having been in 38/146, is strongly IDed with the show, kinda like Betty White was to Mary Tyler Moore!
Hawaiian Eye (October 7, 1959-1963): One of the oldest series whose female lead is living, this P.I. show starred Connie Stevens (b. August 8, 1938) as Cricket Blake, and she was on 120/134 episodes. BTW, Tina Cole (b. August 4, 1943) was Sunny Day on 9/134. Emmys should be awarded for character names.

Mr. Lucky (October 24, 1959-1960): Short-lived show has long-lived Pippa Scott (b. November 10, 1935) in 8/39 episodes.