Larry Blyden-the Whats My Line host I believe waas doing dramas for PBS at the time of his 1975 death, such as the one he had done with Carol Burnett on alcoholics.
...Blyden had also emceed the successful pilot for the ABC game show
Showoffs the week before he took a trip to Morocco, where he was killed in an auto mishap. Goodson-Todman, the producers of
Showoffs, hurriedly replaced Blyden with Bobby Van less than a month before the series was to replace
Password on the ABC schedule...
..and speaking of Bobby Van, I believe he had died of a brain tumor during the time he was the host of "Make Me Laugh". Now I am not sure if the show was still in production at the time of Van's July 1980 death but I do know that the show was still being seen in many markets such as Baltimore during the latter part of the summer of 1980, even after Bobby's death.