I believe Phyllis Coates who played Mrs. Donaldson is one if not the oldest person still alive who appeared on the show.

Anyone older?

One person I found was the last actress to play Gwen Rutherford, Margaret Stewart (Parking Attendants). Unfortunately I couldn't find her age.

Majel Barrett (Beaver and Violet) and Helen Parrish (the original, as Geraldine), the others, are gone.

It's difficult to find people from that generation who are still with us.

Phyllis Coates was in the first season of Superman, as Lois Lane, and must be very old.

Kathleen O'Malley, who played the woman who let Wally and Eddie use the phone for their gag on Lumpy in Wally's Prac. Joke (the cast showed her as Mrs. Halloran but I don't think she was named in the script), died just this year, in Feb. (age 94)

She beat out Phyllis while she was alive. Now it’s Phyllis who is 92.

I see where Phyllis is still alive so she gets the medal. Hey did anyone know that she was married to Norman Tokar at the time New Neighbors was filmed. She was married from 55 to 58. He put her in the episode. I can hear her now “Oh Normie I see where there’s a part for a woman new to the neighborhood so can I do it?”

Noel Neill, who followed Phyllis Coates as Lois Lane in the Superman TV show, also lived to a very old age, 95. Interesting about Norman Tokar--you learn something every day.

Interesting unrelated fact: Marsha Hunt, who played a meddlesome aunt in a My Three Sons episode around 1967, is 102.