John Francis Dunsworth was a Canadian actor and filmmaker. He was best known for playing trailer park supervisor Jim Lahey, the antagonist on the comedy series Trailer Park Boys (2001–2018). His other roles included the mysterious reporter Dave Teagues on the supernatural drama series Haven (2010–2015) and Officer McNabb in the CBC film Shattered City: The Halifax Explosion (2003). He also had extensive experience in regional theater.

James "Jim" Lahey, better known as Mr. Lahey, is a fictional character in the television series Trailer Park Boys. Portrayed by the late John Dunsworth, he is the main antagonist of the series along with his on again/off again boyfriend Randy. He was created by series creator Mike Clattenburg. After Dunsworth's death in October 2017, there was speculation that he would not appear in future Trailer Park Boys releases. He posthumously appears in the first two seasons of the animated series. John Dunsworth's daughter Sarah Dunsworth-Nickerson, tweeted that her father's real voice was used in the animated series. Jim also appears in four films; one short, and three feature length. Before the show, he appeared in the short film One Last Shot (1998). He appears in the feature-length films: Trailer Park Boys: The Movie (2006), Countdown to Liquor Day (2009), and Don't Legalize It (2014).