|Gone with the Wind (1939) [Melanie Hamilton Wilkes]: Dies of complications from a miscarriage. She is shown on her deathbed, talking to Vivien Leigh, though her actual death occurs off-screen shortly afterwards, while Vivien is talking to Leslie Howard in the other room.
My Cousin Rachel (1952) [Rachel Sangelletti Ashley]: Falls to her death after Richard Burton sabotages a bridge; he rushes to try to stop her after realizing that she's innocent, but arrives too late to save her. (It's been so long since I've seen this movie, I can't recall whether her body was shown or not.) (Thanks to Ioana)
Hush...Hush, Sweet Charlotte (Cross of Iron; What Ever Happened to Cousin Charlotte?) (1964) [Miriam Deering]: Crushed to death (along with Joseph Cotten) when Bette Davis drops a large piece of masonry on them. (Thanks to Mac)
Pope Joan (The Devil's Impostor) (1972) [Mother Superior]: Crucified upside-down when the Normans attack the convent. (Thanks to Cullin)
The Swarm (1978) [Maureen Schuster]: Killed in a train crash when the train is derailed by the swarm of bees. (Thanks to Eugene)