|Ever in My Heart (1933) [Mary Archer Wilbrandt]: Reportedly commits suicide (I don't know the exact method). (Thanks to Sally)
Double Indemnity (1944) [Phyllis Dietrichson]: Shot in the stomach by Fred MacMurray.
The Strange Love of Martha Ivers (1946) [Martha Ivers O'Neil]: Commits suicide by pulling the trigger herself when Kirk Douglas holds a gun to her stomach.
Sorry, Wrong Number (1948) [Leona Stevenson]: Killed (exact method unclear) by a hitman in her bedroom; we only see her hands clutching at the nightstand during the murder. (Thanks to Sally)
The File on Thelma Jordon (Thelma Jordon) (1950) [Thelma Jordon]: Reportedly killed in a car crash. (Thanks to Sally)
Blowing Wild (1953) [Marina Conway]: Reportedly killed in an explosion when a nearby oil well is hit by a grenade, after she suicidally walks through the middle of the battle. (Thanks to Aurio)
The Violent Men (The Bandits; Rough Company) (1955) [Martha Wilkison]: Reportedly shot to death (off-screen). (Thanks to Anonymous)
The Maverick Queen (1956) [Kit Banion]: Reportedly shot in a shoot-out with outlaws as she tries to protect the wounded Barry Sullivan; she dies in Barry's arms shortly afterwards. (Thanks to Anonymous)
Rawhide: The Captain's Wife (1960) [Nora Holloway]: Reportedly shot in the back during a shoot-out with Native Americans; she dies in Eric Fleming's arms shortly afterwards. (Thanks to Anonymous)
The Thorn Birds (1983) [Mary Carson]: Reportedly dies of natural causes. (Thanks to Sally)