John William Ferrell (/ˈfɛrəl/; born July 16, 1967) is an American actor, comedian, writer, and producer. He is known for his leading man roles in comedy films and for his work as a television producer. Ferrell has received various accolades, including six Primetime Emmy Awards and a British Academy Television Award, in addition to nominations for two Golden Globe Awards and for a Tony Award. In 2011, Ferrell was honoured with the Mark Twain Prize for American Humor. In 2015, he received a star on the Hollywood Walk of Fame and was named the year's best comedian in British GQ.

Ferrell first established himself in the mid-1990s as a cast member on the sketch comedy series Saturday Night Live, where he performed from 1995 to 2002, and has subsequently starred in a string of comedy films. After starring in the 2003 comedy film Old School, Ferrell became 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 founded the comedy website Funny or Die in 2007 with his former writing partner, Adam McKay.