He borrowed a 16mm camera, cut up his mother's old fur coat to make a bear model, and made a film about himself and his dog being menaced by a bear. His parents were so impressed that he was spared a spanking for ruining the fur coat.
During World War II, Harryhausen joined Frank Capra's film unit, which made the "Why We Fight" propaganda series. After the war, he made stop-motion versions of fairy tales that prompted his idol, O'Brien, to hire him to help create the ape in "Mighty Joe Young," an achievement that won an Academy Award. Harryhausen then embarked on a solo career.
In contrast to the millions spent on digital effects today, Harryhausen made his magic on a shoestring. His first effort, "The Beast from 20,000 Fathoms" (1953), cost $250,000 for the entire film. He commented wryly in 1998: "I find it rather amusing to sit through the on-screen credits today, seeing the names of 200 people doing what I once did by myself."
He found ways to economize. For "It Came from Beneath the Sea" (1955) he employed an octopus with six tentacles instead of eight. That saved time.
"Jason and the Argonauts" (1963) demonstrated the intricacy of Harryhausen's tricks. He had three live actors dueling seven skeletons. It took four months to produce a few minutes on the screen.
Other notable achievements included the film "Earth vs. the Flying Saucers," where aliens slice through the Washington Monument and crash into the U.S. Capitol. He also was behind "The Golden Voyage of Sinbad," where a one-eyed centaur battles a part-lion, part-eagle creature known as a griffin.
Harryhausen's last film, "The Clash of the Titans" (1981), was the only one with a big budget and major cast: Laurence Olivier, Maggie Smith, Burgess Meredith, Harry Hamlin and Claire Bloom. Hamlin as Perseus struggled to tame a white-winged Pegasus and to battle the snake-haired Medusa.
After the film, Harryhausen retired, explaining, "I was tired of spending year after year in a dark room."
He and his wife, Diana, moved to London, where he fashioned bronze replicas of his movie creations. He often appeared at fantasy conventions and in 1992 received a special award from the Motion Picture Academy.
Darren G. Davis, the publisher of Bluewater Productions, called Harryhausen's death the passing of an icon.
"From the first time I saw 'Jason and the Argonauts' and 'Clash of the Titans,' I was spellbound," he said of the man whose imprint is found on Bluewater's "Ray Harryhausen Presents" comic anthology. "I feel so blessed for the opportunity to have worked with him through the years on numerous comic adaptations, graphic novel sequels and other projects based on his visionary work."
Bradbury, who had met Harryhausen in 1938 and wrote the story for "The Beast from 20,000 Fathoms," one said of the film master: "He and I made a pact to grow old but never grow up - to keep the pterodactyl and the tyrannosaurus forever in our hearts."
Harryhausen is survived by his wife and daughter, Vanessa.