|The Twilight Zone: To Serve Man (1962) [Chambers]: Killed (off-screen) by the Kanamit aliens, shortly after the end of the episode; the episode ends with him being taken to their home planet to be slaughtered. (Thanks to Stephen)
The Wild Wild West: The Night of the Puppeteer (1966) [Zachariah Skull]: Scalded to death after Robert Conrad shoots the steam pipe behind Lloyd in Lloyd's underground lair. (Thanks to Stephen)
Point Blank (1967) [Frederick Carter]: Shot to death by James B. Sikking, who had mistaken him for Lee Marvin. (Thanks to Michael)
Satan's School for Girls (1973) [Professor Delacroix]: Drowned and/or beaten to death when a group of students attack him with oars after he falls into the lake. His body is shown afterwards when Pamela Franklin discovers him placed in the back seat of a car.
Ellery Queen: The Adventure of Colonel Nivin's Memoirs (1975) [Colonel Alec Nivin]: Stabbed to death (off-screen) by Rene Auberjonois in a gentlemen's club; his body is shown afterwards when Gretchen Corbett discovers him.
Darkroom: Daisies (1981) [Dr. John Michaelson]: Shot to death by Rue McClanahan in his laboratory, after she learns that he's been having an affair with Elizabeth Halliday.
Dynasty: The Wedding (1982) [Cecil Baldwin Colby]: Dies of a heart attack in the hospital after completing the wedding ceremony with Joan Collins. (Thanks to Johan)