La Belle Dame sans Merci is a 1819 poem of a femme fatale by John Keats
The narrator discovers a dying Knight who tells his story: He had found & made love to a beautiful and mysterious woman;too late he found out she's a witch who has drained him of his soul/lifeforce with black magic in order to retain her youth.
Other similar stories with the same general theme are:Helen Of Troy (Kolchak: The Night Stalker); Pamela Morris (The Twilight Zone); Lady Die (Friday the 13th: The Series); Mary Beth (Freakazoid!); Mirror Queen (The Brothers Grimm);Pamela Dare (The Adventures of Superboy); Star Trek animated cartoon series "The Lorelei Signal" Kirk, Spock and McCoy are captured by beautiful femme fatales who use science to drain the lifeforce out of the male crewmen to remain young; "Favorite Son" (Star Trek: Voyager) Ensign Kim finds his life energy drained by an all female society; "Otherworld (TV series) episode ["Paradise Lost"] in which beautiful femme fatales who use science to drain the lifeforce out of males to remain young;"Ark II" 1976 [last episode] "Orkus" where the crew rapidly ages after encountering a group of Immortals; "The Quality of Mercy" [Babylon 5] a wounded insane seriel killer named Karl Mueller tried to force a terminally ill physician to use a alien healing device to heal him or he would harm her and her daughter; the phyisican used the device to transfer her disease to him and then used it to drain his life energy from him until he literally dropped dead. A 1990 comic movie (Based on Twilight Zone "Queen of the Nile") had a vain woman using and sacrificing dozens of willing men to maintain her beauty until to her shock and horror one man refuses her..and she becomes older!