Willis Henry O'Brien (1886-1962),
animator whose most popular creation was the eponymous ape in the 1933 classic movie,
King Kong. Though by no means the first person to employ
stop-motionanimation in movies, he is rightly considered a pioneer of the technique, having pushed its boundaries farther than anyone except his apprentice,
Ray Harryhausen.
According to Orville Goldner and George Turner's book, The Making of King Kong (lamentably out-of-print), O'Brien had been sculpting figures of boxers for the 1915 San Francisco World Fair when his brother started moving the arms of one fighter, saying "My fighter can beat yours." Willis, who had access to a borrowed newsreel camera, made a short film where the mannikins appeared to be fighting each other.
The motion was crude and jerky, but it inspired O'Brien, who soon produced the short film The Dinosaur and the Missing Link, featuring wooden armatures fleshed out with clay. The Thomas A. Edison Company bought the film for theatrical distribution, and O'Brien, realizing the commercial and artistic potential for the technique, formed his own production company, Mannikin Films, Inc. Mannikin Films produced a string of stop-motion short features, with titles like Prehistoric Poultry, Curious Pets of our Ancestors, and Nippy's Nightmare. This last one was the first movie to feature both live-action and stop-motion characters, though not ever in the same shot.
O'Brien, along with Marcel Delgado, a Mexican-born fellow sculptor he had met while taking night classes at the Otis Art Institute, continued improving on the animation technique, culminating in the 1925 feature, The Lost World, based on the novel by Arthur Conan Doyle (of Sherlock Holmes fame). Using double exposure and masking off selected portions of the frame, O'Brien was able to pull of the convincing illusion of prehistoric monsters menacing a party of explorers, including star Wallace Beery. (Yes, the same Wallace Beery alluded to in the Coen Brothers movie Barton Fink.)
Then, in 1931, Merian C. Cooper, producer of semi-documentary films like Chang and Creation, contacted O'Brien with his idea for a film that would eventually become King Kong. Cooper had originally planned to shoot a film in which a live gorilla, captured in Africa, would be brought to Komodo to fight the enormous lizards (the so-called Komodo Dragons) there. When faced with the impracticality of the venture, Cooper changed approaches, and began formulating the story for Kong. He approached O'Brien ("Obie" to his friends), and O'Brien, along with Delgado, conceptual artist Mario Larrinaga, and a team of studio technicians, pulled together to produce the story of the love-smitten giant ape.
The rest of the story is well-known. Kong went on to become a landmark picture, listed as one of the 100 Greatest American movies by the American Film Institute. It was remade in 1976, poorly, by Dino de Laurentis, and talk was bandied about in the late 1990s for a new production helmed by Peter Jackson of Heavenly Creatures and Lord of the Rings fame.
O'Brien, however, did not have so successful a career after King Kong, even though Cooper would hire him when he could. He found work sporadically in the late 30s and 40s, with his most noteworthy production in this period being the original Mighty Joe Young, on which he worked with the young Ray Harryhausen. He ran into financial difficulties, and died of a heart attack on November 8th, 1962 while working on the film, It's a Mad, Mad, Mad, Mad World. He is far from famous in the general movie world, but legendary among those who care about the power of cinematic illusion.
(Note: most of the information above was condensed from the afore-mentioned book, The Making of King Kong. Plans had been made to re-issue an updated version of the book, plans which have, to date, not materialized. If you can find a copy, it is well worth the reading to cinephiles.)