Gregory Hill (May 21, 1941 – July 20, 2000), 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 (a.k.a. Lord Omar Khayyam Ravenhurst) 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.

Gregory H. Hill was born in California on Wednesday, May 21, 1941. He worked for Western Union while a young man in the Southern California area of Whittier, California.

Around 1958 or 1959 while still a teenager, he, Kerry Thornley and others began working on the Discordian religion.

In 1965, the first edition of Principia Discordia was printed, allegedly in five copies. The most famous edition was the fourth.

Hill spent much of his life working for Bank of America as a computer programmer, and moved to the San Francisco Bay Area. He had apparently visited there while a child.

Robert Anton Wilson stated, in the lecture "The I in the Triangle" from 1990, that Greg Hill was at the time the head of a large computer facility owned by one of the largest banks in the United States.

A designer of one of the early video games, Hill wrote about computers including editing a computer-oriented newsletter. He also published an article proposing using a computer to transmit signals to remotely control robots.

He was married to Jeanetta Ross; they later separated and may have divorced.