When "Dr. Jekyll and Mr. Hyde" premiered in Chicago in 1908, produced by the Selig Polyscope Company, the film was the first American real horror movie every shown. This film is lost, as well as its sequel, 1909's "The Modern Dr. Jekyll," also produced by Selig.
The earliest existing print of a movie based on the 1887 Robert Livingston Stevenson's novel "Strange Case of Dr. Jekyll and Mr. Hyde" is the 1912 "Dr. Jekyll and Mr. Hyde," produced by Thanhouser Studios. Actor James Cruz, seen in the lead of the earlier "She," is named in the credits for playing both roles as the researcher Dr. Jekyll, soon to be married, and his evil alter ego Mr. Hyde, which the good doctor turns into by drinking a concoction of liquid.
The 1908 film claims to have been based directly on the Stevenson novel while the Thanhouser version takes its cue from the subsequent successful stage play, "Dr. Jekyll and Mr. Hyde, or a Mis-Spent Life." There is some controversy as to who actually plays the shorter Mr. Hyde, one of the few Jekyll movies (and there are a great many) where Hyde is considerably shorter than his counterpart. A Thanhouser Studio actor Harry Benham is attributed by some to have played Mr. Hyde even though he isn't credited in the opening title. The viewer can spot the height difference between the taller Cruze, playing Dr. Jekyll, and the shorter Mr. Hyde.
The Dr. Jekyll and Mr. Hyde theme has since been the main thread in a wide variety of movies, some which one wouldn't think would be related. They include "The Nutty Professor," "Van Hesling," "Edge of Sanity," "I, Monster," "The Ugly Duckling (cartoon)", and "Pagemaster."