"Not Fair" is a song by British recording artist Lily Allen from her second studio album, It's Not Me, It's You (2009). Written by Allen and Greg Kurstin, the song was released as the second single from the album on 20 March 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.

Lily Rose Beatrice Allen is an English singer-songwriter and actress. She is the daughter of actor Keith Allen and film producer Alison Owen. Her musical career began in 2005 when she was signed to Regal Recordings and began publishing her vocal recordings on the social networking site Myspace; their popularity resulted in airplay on BBC Radio 1. Her 2006 debut commercial single, "Smile" reached number one on the UK Singles Chart by July of that year and received double platinum certification by the British Phonographic Industry (BPI). Her debut studio album, Alright, Still (2006) explored ska and reggae. It was met with positive critical reception, peaked at number two on the UK Albums Chart, and sold over 2.6 million copies worldwide. The album also yielded a Grammy Award nomination for Best Alternative Music Album and spawned the follow up singles "LDN" and "Alfie".