Watching 60s TV shows on Me-TV often turns into a game of "Who's that TOS guest actor?" One that particularly tickled my geek fancy was an episode of The Rifleman
--a series that put Paul Fix to better use as regular character Micah Torrance, marshal of North Fork. This episode also guest-starred John Hoyt as a VOTW--both TOS pilot doctors in one place! And that's not even the episode's guest star claim to fame--It also featured Dennis Hopper. Searching IMDB, it seems that John Hoyt appeared in another episode as a different character.
And if you're going to bring Jeffrey Hunter's resume up, it's always worth noting that you can usually catch him on the tube at least twice a year as Jesus in King of Kings
EDIT: Other noteworthy ones that pop into my head:
--Caught Sherry Jackson in episodes of The Rifleman
and Dobie Gillis
within a week or so of each other, IIRC. She actually got credited in the onscreen "Info" data in the former, and was particularly striking as a dominatrix-y character in the latter.
--Also, caught an episode of Route 66
in which the "where have I seen her before?" thing was really bugging me until I realized from the female guest star's voice that she was Joanne Linville, the Romulan commander in "The Enterprise Incident". Her husband in the episode had been instantly recognizable--Leslie Nielsen; and to top it off, I was further into the episode when I realized that the tyke playing their son was none other than little Ronny Howard!