Title says it all. Add to the list.
David Letterman
Johnny Carson
Steve Allen
Lucille Ball
Smothers Brothers
In addition to all the above, I add Ross Martin. I loved him on Wild, Wild West, and remember sadly the day I found a newspaper with his obituary on the bus riding home from work in 1981.
Probably also Jack Lord as the* real *Steve McGarret on the original Hawaii Five-O.
And of course, Leonard Nimoy, James Doohan, and now Grace Lee Whitney.
Peter Falk.
Oh, yeah! :smack:
James Garner, as both Maverick and Jim Rockford!
Elizabeth Montgomery as Samantha Stevens.
Dick York as Darrin Stevens.
Robert Stack as Eliot Ness.
Jim Henson
Bob Hope
Phil Hartman
But not DeForest Kelley?
David Brinkley
Walter Cronkite
Frank McGee
Ernest Borgnine as Lt Cdr Quentin McHale.
Tim Conway as Ensign Charles Parker. (Oops; I see Tim is still alive, praise the Lord!)
Vic Morrow as Sgt Orville “Chip” Saunders.
Rick Jason as Lt Gil Hanley.
Dick Peabody as PFC Littlejohn.
Duh! Of course Dee Kelley! :smack:
I assume the OP didn’t mean to exclude people who were still alive but no longer on TV, given that its first example was David Letterman (and also included the Smothers Brothers).
Pretty much the entire cast of Hogan’s Heroes, except for Robert Clary.
Whit Bissel of ***Star Trek ***and ***Time Tunnel ***fame.
Ted Bessell as Don Hollinger on That Girl.
Very true! Missing them is the main thing, living or dead.
Good point! Tim Conway, then! 
Most of the cast of Gilligan’s Island.
Ray Zaremba and Lee Meriwether, also of Time Tunnel fame.
Lee was also Catwoman, as was Julie Newmar!
John Belushi
James Darren and Robert Colbert, also of Time Tunnel fame.
My favorite show in sixth grade, along with Rat Patrol with Christopher George and Gary Raymond.
Patrick MacNee and Diana Rigg on The Avengers.
Howard Cosell
Dandy Don Meredith
Jim McKay
Dick Clark
Ed Sullivan
Art Fleming
Richard Dawson
Gene Rayburn
For a good memory jogger – and some great fun interviews – check out
Archive of American Television