John William Ferrell (; born July 16, 1967) is an American actor, comedian, producer, and writer. He first established himself in the mid-1990s as a cast member on the NBC sketch comedy show Saturday Night Live, where he performed from 1995 to 2002, and has subsequently starred in comedy films such as Elf (2003), Anchorman: The Legend of Ron Burgundy (2004), Kicking & Screaming (2005), Talladega Nights: The Ballad of Ricky Bobby (2006), Semi-Pro (2008), and Land of the Lost (2009). He founded the comedy website Funny or Die in 2007 with his writing partner Adam McKay. Other notable film roles include The Other Guys (2010), The Campaign (2012), Get Hard (2015), Holmes & Watson (2018), and the animated films Curious George (2006) and Megamind (2010).

Ferrell is considered a member of the "Frat Pack", a generation of leading Hollywood comic actors who emerged in the late 1990s and the 2000s, including Jack Black, Ben Stiller, Steve Carell, Vince Vaughn, Paul Rudd, and brothers Owen and Luke Wilson. He received an Emmy Award nomination for his work on Saturday Night Live, and three Golden Globe Award nominations for acting in The Producers (2005) and Stranger than Fiction (2006) and for producing Vice (2018). He was also named the best comedian of 2015 in the British GQ Men of the Year awards. Ferrell received a star on the Hollywood Walk of Fame on March 24, 2015.