Hyperion is also the name of the publishing arm of the Walt Disney Company.
It was created in 1991 and is the imprint found on most non-fiction, Disney-sanctioned titles. Children's books and other fiction are usually published under other imprints. Hyperion also publishes plenty of non-Disney-related books in numerous genres.
The Hyperion imprint was named after the location of the Walt Disney Studios from 1926 through 1939. The studio on Hyperion Avenue in Los Angeles saw the company grow from its humble beginnings with the Alice comedies through the creation of Mickey Mouse and his friends, all the way through the production of Pinocchio; the company's runaway success forced a move to Burbank in late 1939, just six weeks before Pinocchio's release.
Hyperion's web site is (http://www.hyperionbooks.com/). In their own words:
Hyperion, which was founded in 1991, publishes general-interest fiction and nonfiction books for adults. It includes the Talk Miramax, ESPN Books, ABC Daytime Press, Hyperion East and Theia imprints.