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).

Trailer Park Boys is a Canadian mockumentary television sitcom created by Mike Clattenburg that began airing in 2001 as a continuation of his 1999 film bearing the same name. The show follows the misadventures of a group of trailer park residents, including two lead characters in and out of prison, living in the fictional "Sunnyvale Trailer Park" in Dartmouth, Nova Scotia. The series premiered on Showcase on April 20, 2001, and originally ran for seven seasons before concluding with a one-hour special on December 7, 2008. The series spawned three films: The Movie, released on October 6, 2006; Countdown to Liquor Day, released on September 25, 2009; and Don't Legalize It, released on April 18, 2014.