Is it just me, or does this thread no longer match the subject? The subhead specifies "regulars," but as it goes on, many of the celebs listed were hardly regular faces on any game show (Werner Klemperer? Ja'net DuBois? Jill Whelan?).
I'll throw in my suggestion: The Dick Van Dyke Show gave us both Rose Marie and Morey Amsterdam as future Hollywood Squares regulars.
Werner was on syndie WML a few weeks a year. If you check imdb, you'll see he did quite a few game shows in the early '70s. I'm old enough to remember seeing him more often than somebody younger might. In what could be called an ironic coincidence, you could tune into NBC and CBS at 11:30 am in the late '60s and see Rose Marie and Morey Amsterdam either on HS or DVD reruns.