Rin Tin Tin
German shephard dog found in a German trench during World War I by an American captain; the captain brought him back to Los Angeles and trained him to work in films. Remarkably, the dog -- first onscreen in The Man from Hell's River (1922) -- became extremely popular in a series of films and serials, and his films were the main source of revenue for Warner Brothers for several years; he thus received top billing, and received 12,000 fan letters a week. The films, mixing drama, comedy, and adventure, were often written by Darryl F. Zanuck. The dog went on to appear in a number of sound productions; after his death, he was succeeded by Rin Tin Tin Jr.