|Land of the Pharaohs (1957) [Princess Nellifer]: Suffocated or starved to death (off-screen) after being entombed alive inside the pyramid; the movie ends with her trapped inside. (Thanks to Richard and Nemanja)
Star Trek: The City on the Edge of Forever (1967) [Edith Keeler]: Hit by a truck while crossing the street; the scene cuts away just before the impact, then her body is shown lying in the street.
Mission: Impossible: Nicole (1969) [Nicole Vedette]: Shot in the stomach by Logan Ramsey. (Thanks to Energman and Chris)
Quest for Love (1971) [Ottilie/Tracy Fletcher]: Playing a dual role as two parallel-universe counterparts, "Ottilie" dies of heart failure in Tom Bell's arms. ("Tracy" survives the movie.)
Fear in the Night (Dynasty of Fear; Honeymoon of Fear) (1972) [Molly Carmichael]: Shot to death by Ralph Bates (who had mistaken her for Peter Cushing) while she's gagged and tied to a chair and covered with a sheet. (Thanks to Andrea)
Tales from the Crypt (1972) [Joanne Clayton]: Murdered (off-screen) by an escaped maniac in a Santa Claus suit. The scene ends as the attack begins, then immediately cuts to Joan standing with the other "tourists" in Ralph Richardson's crypt. (It's revealed at the end that they are all ghosts, and that their stories weren't warnings of the future but accounts of what had already happened to them.)
Tales That Witness Madness (1973) [Bella Thompson]: Killed (off-screen) by an intelligent, mobile plant.
Dark Places (1974) [Sarah]: Strangled by the deranged and/or possessed Robert Hardy (re-enacting the years-earlier murder of Jean Marsh). Her body is shown again later on when her brother (Christopher Lee) discovers her.
I Don't Want to Be Born (The Baby; The Devil Within Her; The Monster; Sharon's Baby) (1975) [Lucy Carlesi]: Stabbed in the chest by the possessed baby through the crack in the doorway as she tries to hold the door closed.
Gibbsville: Andrea (1976) [Andrea]: Commits suicide by jumping from a window. (Thanks to Gordon)
Empire of the Ants (1977) [Marilyn Fryer]: Killed by the giant ants. (Thanks to PortsGuy)
Fearless (Poliziotto senza paura; Fatal Charm) (1977) [Brigitte]: Shot in the chest by Alexander Trojan after he knocks out Maurizio Merli; we only see the flash of the gunshot reflected in a picture frame as Maurizio loses consciousness. Her body is shown afterwards when Maurizio wakes up and discovers her lying on the couch. (Nudity alert: Topless)
The Wild Women of Chastity Gulch (1982) [Annie McCulloch]: Dies of natural causes. (Thanks to Robert)
Faerie Tale Theatre: Hansel and Gretel (1983) [The Witch/The Evil Stepmother]: Presumably pushed into her own oven by Bridgette Andersen. (Thanks to PortsGuy)