William Mastrosimone (born August 19, 1947) is an American playwright and screenwriter from Trenton, New Jersey.
His plays include The Woolgatherer, Extremities, Shivaree, and Cat's Paw.
Other plays include The Afghan Women and Nanawatai, upon which the film The Beast is based.
Two recent plays are Sleepwalk, a story again focusing on the traumas of modern teenage life, and "Dirty Business", a play about a party girl caught between the mafia and the newly elected President of the United States.
His play Bang Bang You're Dead is being toured by 'Playground Theatre Project' with students from Actor's Playground School of Theatre (in NJ), directed by Ralph Colombino, based in the Tri-State Area.