Real world article
(written from a production point of view)
Richard Dix (July 18, 1893-September 20, 1949) was an actor who appeared in many pictures for RKO between 1929 and 1943.
The original shooting script for the Star Trek: The Original Series first season episode "The City on the Edge of Forever" had his name in place of Clark Gable's. It was changed because Gable was more well known, despite him not being a leading man at the time that the episode was supposed to take place. [1]