William Gray is a Canadian screenwriter. He won the Genie Award for Best Adapted Screenplay for the 1980 supernatural horror film The Changeling, which he co-wrote with Diana Maddox.
Born in Toronto, Gray worked as a rock music critic for the Toronto Sun before beginning a career in insurance. He was later hired by Paul Lynch to write the screenplay for the sports drama Blood and Guts (1978).
Gray co-wrote the screenplay for the supernatural horror film The Changeling (1980) with Diana Maddox. Gray and Maddox won the Genie Award for Best Adapted Screenplay for The Changeling.
Gray worked as a screenwriter for several other projects for director Paul Lynch, including the slasher film Prom Night (1980), and the horror films Humongous (1982) and Cross Country (1983). In 1984, he wrote the screenplay for the science fiction film The Philadelphia Experiment with Michael Hanover, followed by Black Moon Rising (1986), which he co-wrote with John Carpenter and Desmond Nakano.