The potential for Claymation began in 1897, with the invention of plasticine. Unlike clay, the material remained flexible indefinitely, allowing animators to manipulate it as they wished. It appeared in a number of projects--along with similar stop-motion efforts like the great "King Kong"--but the process of animation was so time-consuming that it was only used sporadically.
Claymation first broke out through the efforts of an animator named Art Clokey. He created a little green Claymation character named Gumby who, along with his orange pony Pokey, became a huge hit on children's television. Gumby ran from 1956 to 1963 and its distinctive look paved the way for future animators to follow.
The medium received a further shot in the arm with the rise of Will Vinton, a former Cal Berkeley architecture student with a fascination for Claymation. Indeed, technically speaking, Vinton is the only producer of "Claymation," since he's copyrighted the term. Starting with a 1975 short entitled "Closed Mondays," he and his studio produced numerous Claymation shorts (and one feature film, "The Adventures of Mark Twain") which elevated public perception of the medium to new heights.
Vinton's most famous creation was undoubtedly the California Raisins: anthropomorphic fruit who extolled the virtues of raisins in a series of commercials while crooning Marvin Gaye's "I Heard it Through the Grapevine." The ads were a sensation when they first appeared in 1987 and spawned a number of spin-offs, including a Saturday morning cartoon. Their success helped cement Claymation's status as a commercially viable medium, and allowed a host of other animators to try their hands at it.
While Vinton was conquering the world, another Claymation studio began working over in England. Aardman Animations began in 1976, and was able to exploit the growing popularity of the medium on a level equaling Vinton's. Its first notable success was with the Peter Gabriel video "Sledgehammer"--consisting almost entirely of Claymation figures--and they won an Oscar in early 1990 for their animated short "Creature Comforts." Their greatest characters appeared later in the decade: a lunk-headed inventor named Wallace and his quietly competent dog Gromit. The duo netted Aardman another three Oscars: two for its shorts and one for its first feature, "The Curse of the Wererabbit."