John B. "Jack" O'Brien (December 13, 1884 – August 15, 1936) was an American actor and film director of the silent era. He appeared in more than 80 films between 1909 and 1936. He also directed 53 films between 1914 and 1926.
According to two sources, in July 1911, O'Brien was lured away from Essanay to direct the film The Life of Buffalo Bill, featuring Buffalo Bill himself.[2][3] According to one of these sources, the book Buffalo Bill on the Silver Screen: The Films of William F. Cody, O'Brien had to shoot the film while the Wild West show was on tour.[3] It was supposedly the first[2] or one of the first[3][4] five-reel feature movies. However, the opening credits of the film itself state that it is only three reels long.[5] (To confuse the issue even further, there is another 1912 film with exactly the same title, directed by Paul Panzer.[6])