|Dick Durock (1937 - 2009)|
|The Enforcer (1976) [Karl]: Shot in the chest in a shoot-out with Clint Eastwood on Alcatraz.
The Incredible Hulk: The First, Part 2 (1981) [Frye's Creature]: Playing another "Hulk" creature, he is shot by Billy Green Bush; in death, he transforms back into his human form (Harry Townes). (Thanks to Michael)
(Note: As a professional stunt performer, Dick has probably "died" in place of several other actors, though I don't know any specific examples.)