Peter Alexander McWilliams (August 5, 1949 – June 14, 2000) was an American self-help author who advocated for the legalization of marijuana.
McWilliams was born to a Roman Catholic family in Detroit, Michigan, USA. His father worked as a supervisor at a drugstore and his mother was a part-time salesperson. He attended Allen Park High School and Eastern Michigan University and later enrolled at Maharishi International University. At the age of 17 he wrote a collection of poems called Come Love with Me and Be My Life, which he self-published under the name Versemonger Press.
He wrote The TM Book in 1975 with Denise Denniston, which was at the top of the New York Times bestseller list for three weeks. In 1976, he wrote TM: An Alphabetical Guide to the Transcendental Meditation Program with Denise Denniston and Nat Goldhaber. He later wrote the book, TM, with Harold H. Bloomfield and later co-wrote the book How to Heal Depression. McWilliams was active in Erhard Seminars Training with Werner Erhard and Stuart Emory's "Actualizations" large-group awareness training before meeting John-Roger in the fall of 1978.
He wrote nearly 40 books including Surviving the Loss of a Love (1971), The Personal Computer Book (1982) and Life 101: Everything We Wish We Had Learned About Life in School but Didn't (1990). His 1982 book, The Word Processing Book: A Short Course in Computer Literacy was published during the "computer revolution" and was "highly successful." McWilliams was a photographer and a collection of his own photographs were published in October 1992 in a book titled Portraits - A Book of Photographs by Peter McWilliams (1992).
McWilliams was diagnosed with non-Hodgkin's lymphoma in 1996. He was arrested and charged with growing marijuana in 1997. He was released from custody on $250,000 bail and with the "condition that he not use marijuana."