"Not Fair" is a song by British recording artist Lily Allen from her second studio album, It's Not Me, It's You. Written by Allen and produced by Greg Kurstin, the song was released as the second single from the album on 19 February 2009 by Regal Recordings. The song incorporates country music as the lyrics depict sexual frustration. Contemporary critics did not positively receive the song and its theme, some calling it a "pseudo country track" and considering it a strange musical composition. The single peaked in the top 20 of the charts of some European countries and Australia, while scoring Allen's second consecutive top-five hit on both the UK Singles Chart and the Dutch Top 40 (since in the latter "Fuck You" was a commercial success before "Not Fair").
The accompanying music video portrayed a western country theme, with Allen dancing next to a microphone, while back-up singers are dressed as cowgirls, accompanied by cattle and farm birds. The video was shot the same day of the release of the single. It was performed live on different occasions, including Allen's 2009 concert tour.
It was named at number 8 in the Triple J Hottest 100, 2009.