A liar is one who tells lies.

The name Liar may refer to:

• Liar (film), the name used in the UK for Deceiver, a 1997 film starring Chris Penn, Tim Roth, Ellen Burstyn and Renée Zellweger
• Liar (band), a metalcore band from Belgium
• Liar (Harisu album), a 2002 album by South Korean entertainer Harisu
• Liar (The Jesus Lizard album), a 1992 album by noise rock band The Jesus Lizard
• "Liar" (song), a song by Queen from their debut album
• "Liar" (Profyle song), a number-one R&B single by Profyle
• "Liar (It Takes One To Know One)", a song by US rock band Taking Back Sunday
• "Liar", a song by Argent (band) guitarist/keyboardist Russ Ballard, recorded by Argent and by Three Dog Night
• "Liar", a song by Built to Spill from their 2006 album You in Reverse
• "Liar", a song by The Damned from their 1979 album Machine Gun Etiquette
• "Liar", a song by Korn from their 2005 album See You on the Other Side
• "Liar", a song by Yngwie J. Malmsteen from his 1986 album Trilogy
• "Liar", a song by Megadeth from their 1988 album So Far, So Good... So What!
• "Liar", a song by Rollins Band from their 1994 album Weight
• "Liar", a song by The Sex Pistols from their 1977 album Never Mind the Bollocks, Here's the Sex Pistols
• "Liar", a song by The Cross from their 1990 album Mad: Bad: And Dangerous To Know
• Liar!, a short story by Isaac Asimov appearing in the 1950 collection I, Robot
• Liar, a shortlived BBC gameshow hosted by Paul Kaye
• Liar, a 2005 short movie directed by China Moo-Young and starring Glenn Doherty.
• Liar Liar, a 1997 film starring Jim Carrey
• The Liar, a 1991 novel by Stephen Fry
• Liar paradox, one of the classical paradoxes of logic (often referred to as "the liar").

• Liars (band), an indie rock band.
• Liars (album), a 2004 album by Todd Rundgren
• Liars (Liars album), a 2007 album by the band Liars
• The Liars (play), a play by Henry Arthur Jones

"Liar" is the fifth track (first on side two) and, in some territories, second single of English rock band Queen's first album, Queen.

"Liar" was written by Freddie Mercury in 1970 while he was still Freddie Bulsara. It is considered by many to be one of the direct forerunners to "Bohemian Rhapsody", in terms of long melodies, acyclic form and dramatic changes in style and arrangement. It is one of the band's heavier songs, and gets heavier and heavier during the course of the song, starting out with a soft falsetto and ending in heavy guitars and aggressive singing.

As confirmed by the transcription on EMI Music Publishing's Off The Record sheet music for the song, this is the only Queen track to feature a Hammond organ.

In the earlier years of Queen, this song was regarded as one of the most impressive performances of a live show, often going over 8 minutes long. However over time the song eventually fell off the setlist, with the exception of The Works Tour. The song though was cut down to 3 minutes or less.

It is also the favourite Queen track of Kiss frontman Paul Stanley (Classic Rock magazine October 2006)

Liar is the title of a number-one R&B single by group Profyle. The hit song spent one week at number-one on the US R&B chart.

"Liar (It Takes One to Know One)" is the second single in the U.S. from the rock band, Taking Back Sunday's third album. The song is featured on the band's latest album, Louder Now and will be released in the U.S., while their second single in the UK, Twenty-Twenty Surgery will be released. The music video was released on Thursday, September 28, 2006 on MTV2. It was released by Taking Back Sunday as a single/EP in England on November 13th, 2006. The song was released as a single lifted from the band's third album, "Louder Now" and comes with a live recording of "Spin" in the UK single.

"Liar" is sixth track on Rollins Band's fourth full-length album Weight, released in 1994. It was the album's only charting single. It is something of a live favorite for the group, with its spoken verses usually changed from the studio take.

A video clip of this song is also available at YouTube.com.

"Liar" is the fourth single by Eskimo Joe, lifted off their debut album Girl. The video for the "Liar" was nominated for 'Best Video' at the 2002 ARIA awards.