|Walter Pidgeon (1897 - 1984)|
|Dark Command (1940) [William 'Will' Cantrell]: Shot in the chest in a shoot-out with John Wayne.
Blossoms in the Dust (1941) [Samuel 'Sam' Gladney]: Dies of an unspecified illness, with Greer Garson by his bedside.
Madame Curie (1943) [Pierre Curie]: Accidentally hit by a car. (I haven't seen this movie, but I'm familiar with the historic facts, and I've read some IMDB user reviews mentioning that the movie covers Curie's death.)
Forbidden Planet (1956) [Dr. Edward Morbius]: Killed by the strain when he confronts the invisible physical embodiment of his own subconscious; he dies shortly afterwards, after warning Anne Francis and Leslie Nielsen that the planet will soon explode. (Thanks to Mac)
Ellery Queen: The Adventure of the Disappearing Dagger (1976) [Hamilton Drew]: Stabbed to death by Mel Ferrer. (Thanks to Davy)