Leona Louise Lewis (born 3 April 1985) is a British singer, songwriter, actress, model, and activist. Born and raised in Islington, Inner London, she later attended the BRIT School for Performing Arts and Technology in Croydon. Lewis achieved national recognition when she won the third series of the television talent show The X Factor in 2006, winning a £1 million recording contract with Syco Music. Her winner's single, a cover of Kelly Clarkson's "A Moment Like This", peaked at number one for four weeks on the UK Singles Chart and broke a world record by reaching 50,000 digital downloads within 30 minutes. In February 2007, Lewis signed a five-album contract in the United States with Clive Davis's record label, J Records.

Lewis's success continued with the release of her debut studio album, Spirit (2007), which was certified 10× platinum in the UK and became the fourth best-selling album of the 2000s and one of the best-selling albums in UK chart history. The lead single, "Bleeding Love", spent seven weeks at number one in the UK and was the best-selling single of 2007. Her second studio album, Echo (2009), debuted at number one on the UK Albums Chart. In 2011, Lewis released the single "Collide", a collaboration with Swedish DJ Avicii, and her debut extended play, Hurt: The EP. Her third studio album, Glassheart (2012), marked a new creative direction for Lewis, drawing inspiration from dubstep and electronic music. She began to record material for her first Christmas album during her Glassheart Tour, which took place in mid 2013. Christmas, with Love was released later that year and its lead single, "One More Sleep", peaked at number three in the UK.

In 2014, Lewis made her film debut in Walking on Sunshine, and her fourth studio album, I Am, was released the following year. In 2016, she made her Broadway debut as Grizabella in the revival of Andrew Lloyd Webber's musical Cats, and the following year, she signed a modelling contract with Wilhelmina Models. She then collaborated with Calum Scott on the single "You Are the Reason" (2018), and had a recurring role on the American television series The Oath (2019). In 2021, Lewis joined the Paramount+ show Queen of The Universe as a judge.

According to her record company, as of 2021, Lewis has sold over 35 million records worldwide. She is the first British female solo artist to reach the top five with eight singles, surpassing Olivia Newton-John's record of seven. Lewis has won two MOBO Awards, an MTV Europe Music Award, and two World Music Awards. She is also a six-time BRIT Award and three-time Grammy Award nominee. Aside from her music and acting career, Lewis has publicly supported various charitable causes, particularly animal rights; she is also vegan.