|The Strange Love of Martha Ivers (1946) [Walter P. O'Neil]: Commits suicide by shooting himself in the chest, after Barbara Stanwyck kills herself by pulling the trigger of the gun Kirk was holding against her.
Out of the Past (Build My Gallows High) (1947) [Whit Sterling]: Shot to death (off-screen) by Jane Greer in his office; his body is shown lying on the floor afterwards when Robert Mitchum discovers him. (Thanks to Fred and Kelly)
Champion (1949) [Michael 'Midge' Kelly]: Fatally injured during a boxing match, he dies in his dressing room shortly afterwards.
Ace in the Hole (The Big Carnival; The Human Interest Story) (1951) [Chuck Tatum]: Stabbed in the stomach with scissors by Jan Sterling; he dies later on after staggering into the newsroom. (Thanks to Mac, Fred, and Johannes)
Detective Story (1951) [Detective Jim McLeod]: Shot in the stomach by Joseph Wiseman after Joseph grabs another cop's gun in the police station and Kirk tries to face him down; he dies shortly afterwards while talking to his colleagues. (Thanks to Mac and Fred)
Lust for Life (1956) [Vincent Van Gogh]: Commits suicide by shooting himself in the head in the middle of a field.
Gunfight at the OK Corral (1957) [John 'Doc' Holliday]: Dies (off-screen) of tuberculosis; his death is mentioned by another character afterwards. (Thanks to Mac)
The Vikings (1958) [Einar]: Stabbed to death in a fight with Tony Curtis. (Thanks to Fred)
Spartacus (1960) [Spartacus]: Executed by crucifixion; he dies after Jean Simmons shows him his son and says goodbye to him.
The Last Sunset (1961) [Brendan O'Malley]: Shot to death in a gunfight. (Thanks to Fred)
The List of Adrian Messenger (1963) [George Brougham]: Impaled on a piece of farm equipment (a trap he had set intending to kill George C. Scott) after being thrown from a horse. Kirk had been in disguise, but unmasks himself as he dies. (Thanks to Mac and Constantine)
In Harm's Way (1965) [Captain Paul Eddington]: Shot in the head when Japanese fighters open fire on his plane.
The Way West (1967) [Senator William J. Tadlock]: Falls off of a cliff when Connie Sawyer cuts the rope lowering him down (in revenge for Kirk's hanging of Michael Witney). (Thanks to Stephen)
The Brotherhood (1968) [Frank Ginetta]: Shot to death (at his own request) by his brother (Alex Cord). (Thanks to Fred)
There Was a Crooked Man... (1970) [Paris Pittman Jr.]: Bitten by a rattlesnake when he reaches into his money bag. (Thanks to Fred)
A Gunfight (1971) [Will Tenneray]: Shot to death in a gunfight with Johnny Cash. (The movie depicts two possible outcomes to the fight; one with Johnny killing Kirk and one with Kirk killing Johnny.) (Thanks to Fred and Brian)
Jacqueline Susann's Once Is Not Enough (1975) [Mike Wayne]: Killed in a plane crash (off-screen), along with Alexis Smith; we learn of their deaths in a TV news report that his daughter (Deborah Raffin) sees. (Thanks to Fred)
The Fury (1978) [Peter Sandza]: Commits suicide by jumping off of a roof after the death of his son (Andrew Stevens). (Thanks to Fred)
Saturn 3 (1980) [Adam]: Killed in an explosion when he sacrifices himself to destroy the robot. (Thanks to Fred)
Oscar (1991) [Eduardo Provolone]: Dies of old age/natural causes in his bed, leaving control of his crime organization to his son (Sylvester Stallone). (Thanks to Stephen)