John Mahon was an American actor of the stage and screen.

A veteran character actor, Mahon studied classical languages and English literature at the University of Scranton. There, he met actor and playwright Jason Miller and would land his first film role in The Exorcist (1973).

Mahon was best known for playing law enforcement and military types and appeared as such in The People Under the Stairs (1991), One False Move (1992), The American President (1995), L.A. Confidential (1997), Armageddon (1998), Austin Powers: The Spy Who Shagged Me (1999), and Zodiac (2007).

He also guest starred in a number of television shows including The Rockford Files, Kojak, Cagney & Lacey, St. Elsewhere, T.J. Hooker, Knight Rider, MacGyver, Hill Street Blues, Baywatch, Knots Landing, Frasier, The X-Files, JAG, Star Trek: Enterprise, and had a recurring role in Studio 60 on the Sunset Strip.

When he was young, Mahon contracted polio and spent nearly nine months completely paralyzed. Never recovering the full use of his left arm, he would become an inspiration and mentor to actors with disabilities.

Mahon died May 3, 2020, in Los Angeles, California. He was 82.