John Gregory "Jack" Polick (born July 26, 1967) is an American musician and film and television actor.

Polick was born in Geneva, IL and attended the College of DuPage. Polick was a longtime bartender at the Johnny Depp-owned Viper Room in Los Angeles. He is the lead singer of the indie rock combo, Sign Of The Fox.

Polick is also an actor, and has appeared in movies and television. He has made appearances in at least two Johnny Depp-starring films: Blow (2001), and The Brave (1997). Polick played Deputy Cletus in the big-screen remake of The Dukes of Hazzard (2005), starring Johnny Knoxville. He reprised that role briefly, in Jessica Simpson's music video for her cover of Nancy Sinatra's classic, "These Boots Are Made For Walkin'" which Simpson recorded for the film. Polick has also appeared in Knoxville's Jackass: The Movie (2002), Jackass Number Two (2006), Jackass 2.5 (2007) and the TV series Jackass (2002).