3. Irma Bunt (Ilse Steppat - On Her Majesty's Secret Service)
Serving as the number two to Bond's nemesis, Ernst Stavro Blofeld, throughout On Her Majesty's Secret Service, Bunt is the one to discover his infiltration of their plot to distribute a biological agent that would devastate the world's agricultural infrastructure. Bond manages to foil their plan, and proceeds to get married to Diana Rigg's Tracy Di Vicenzo, driving off into the sunset, in what appears to be a happy ending. This is quickly cut short by the arrival of Bunt, who greets the pair with machine gun fire, murdering 007's new bride. More shocking is the fact that, unlike her superior, she never faces justice for her actions, and lives on in infamy as the killer of the only woman that James Bond ever truly loved.