I think everyone is aware of TOS stars/guest stars on The Twilight Zone
, but a few ended up on Serling's final series, Night Gallery
William (Matt Decker) Windom: "They're Tearing Down Tim Riley's Bar"
& "Little Girl Lost"
Glenn (Cochrane) Corbett: "Brenda"
Lou (Lokai) Antonio: "Death on a Barge,"
which was directed by Nimoy.
Leonard (some Vulcan, maybe Stonn...T'Pol?) Nimoy: "She'll Be Company for You"
co-starring Kathryn (Gem / "The Empath"
Jeff (Plasus) Corey: "The Dead Man"
Barbara (Lenore) Anderson: "Fright Night"
Susan (Vina) Oliver: "The Tune in Dan's Cafe"
Gary (Gary Mitchell) Lockwood: "The Ring with the Red Velvet Ropes"
*Charles (Landru / Jaris) Macaulay: "The Funeral"
*Barry (Surak) Atwater: "The Doll of Death"
Louise (Rayna) Sorel: "Pickman's Model" & "The Dead Man"
I'm sure there's more TOS guest stars on NG, but I cannot recall any at the moment.
Macaulay portrayed a very undead "Count" in the Night Gallery episode, and Dracula in Blacula, which starred William (Daystrom) Marshall.
Atwater's best known role was a vampire--Janos Skorzeny in The Night Stalker TV movie.