Ilsa Van Zandt (Marj Dusay; 1936-2020) was the main villainess from "Spirit of Television," episode 3.18 of Friday the 13th: The Series (airdate April 30, 1990) She was a psychic who was terminally ill and on her last days, and before the episode's events, Ilsa (real name Elly Robinson) purchased a cursed TV set, which has the power to allow the deceased to kill people from their past.
Ilsa would use the set to channel the spirits of her customers' loved ones, but once the sessions were completed, Ilsa would send the same spirits to kill them. For each death, Ilsa's life was extended, but that often depended on how long it took to kill her customers. After killing the first victim of the episode, Ilsa's life was extended by 10 days. But regarding her next victim, Genevieve (a friend of Micki's), Ilsa only received one extra day, mainly because Micki, Jack, and Johnny's involvement prolonged the procedure.
Ilsa's next victim, Robert Jandini, was a close friend of Jack's, but her first attempt was thwarted when Jandini escaped. Ilsa visited Jandini (who was haunted by the spirits of his parents) and completed her murderous deed herself, but because she took so long to kill him, she received no time added. Ilsa began feeling the effects of decaying later in the episode, as she was expected to die within a few hours. In a desperate attempt, Ilsa sends Robert to kill Jack, but Micki and Johnny save him, and Ilsa ended up pulled through her TV set and into the spirit world.
- Marj Dusay appeared as KAOS Girl, who is a spy in the 1967 episode "A Man Called Smart, Part 2" for the TV series "Get Smart".
- Marj Dusay appeared as Kara in the 1968 episode "Spock's Brain" for the TV series "Star Trek".
- Marj Dusay appeared as the evil Nazi Baroness von Krimm in the 1969 episode "My Favorite Prisoner for the TV series Hogan's Heroes.