Lily Rose Beatrice Allen (born 2 May 1985) is an English singer-songwriter and actress. 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). Allen's 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".

Her second studio album, It's Not Me, It's You (2009) saw a genre shift in favor of electropop. The album debuted atop the UK Albums Chart and the Australian ARIA Charts, and saw continued positive reception from critics, many of whom noted the singer's musical evolution and maturity. It spawned the hit singles "The Fear", "Not Fair" and "Fuck You". This success saw her receive the Brit Award for British Female Solo Artist at the 2010 Brit Awards. Allen and Amy Winehouse were credited with starting a process that led to the "year of the women" media label in 2009 that saw five female artists making music of "experimentalism and fearlessness" nominated for the Mercury Prize. Her third album, Sheezus (2014) peaked atop the UK Albums Chart once more, while her fourth album, No Shame (2018) peaked at number eight.

Allen also ventured into other careers; in 2008, she hosted her own television talk show, Lily Allen and Friends, on BBC Three before launching her own record label, In the Name Of, in 2011. In 2018, Allen released her autobiographical book, My Thoughts Exactly. As an actress, Allen appeared in the 2019 film How to Build a Girl. In 2021, she made her West End debut in the new play 2:22 A Ghost Story, for which she received a Laurence Olivier Award nomination for Best Actress. She is a daughter of actor Keith Allen and film producer Alison Owen.