|Hawaii Five-O: Beautiful Screamer (1970) [Jane Michaels]: Strangled from behind by Lloyd Bochner. (Thanks to TJ)
Good Guys Wear Black (1978) [Margaret]: Killed in an explosion when Soon-Tek Oh blows up her plane. (Thanks to Rodney)
The Naked Face (1984) [Ann Blake]: Shot by an unseen sniper while walking through a cemetery with Roger Moore.
Falcon Crest: Cataclysm (1986) [Cassandra Wilder]: Revealed to have died in childbirth (off-screen); she was last seen in the 1985 episode Strange Bedfellows and did not appear in this episode, but David Selby learns of her death and visits her grave in this one. (Thanks to PortsGuy)
The Art of War (2000) [Eleanor Hooks]: Shot in the face by an assassin while riding in a car; we only see the blood splattering onto the car's rear window.
It's Always Sunny in Philadelphia: Dennis and Dee's Mom Is Dead (2007) [Barbara Reynolds]: Dies (off-screen) on the operating table during cosmetic surgery. (Thanks to Sherry)