Gregory Hill, better known by the pen name Malaclypse the Younger, was an American author. He is listed as author of the Principia Discordia, which was written with Kerry Wendell Thornley and others. He was also adapted as a character in The Illuminatus! Trilogy (1975). During the early years of circulation of the Principia Discordia, rumors claimed that the author of the book was Richard Nixon, Timothy Leary, or Robert Anton Wilson; or that the book and Malaclypse the Younger were both fictional inventions of Robert Anton Wilson, as with Abdul Alhazred's Necronomicon.

The Principia Discordia is the first published Discordian religious text. It was written by Greg Hill with Kerry Wendell Thornley and others. The first edition was printed using Jim Garrison's Xerox printer in 1963. The second edition was published under the title Principia Discordia or How The West Was Lost in a limited edition of five copies in 1965. The phrase Principia Discordia, reminiscent of Isaac Newton's 1687 Principia Mathematica, is presumably intended to mean Discordant Principles, or Principles of Discordance.