John Paul Lawler (born 4 March 1979), known professionally as Jon Fratelli, is a Scottish musician and singer-songwriter, who is the lead singer of the band The Fratellis. Their debut album, Costello Music (2006) was a success, peaking at number 2 on the UK Albums Chart and spending eighty-three weeks in the UK Top 100. In the United States, it peaked at forty-eight on the US Billboard 200. The Fratellis won the 2007 BRIT Award for Best British Breakthrough Act, and as of March 2018, Costello Music had sold 1,145,000 copies in the UK. Costello Music spawned five successful singles – "Henrietta", "Chelsea Dagger", "Whistle for the Choir", "Baby Fratelli" and "Ole Black 'n' Blue Eyes".

Following the success of Costello Music, the Fratellis released their second album, Here We Stand (2008), before entering a hiatus period. During the hiatus period, Lawler formed Codeine Velvet Club with Lou Hickey. Their self titled debut album was released on 28 December 2009 in the UK and on 6 April 2010 in the US. Lawler returned to perform with The Fratellis, and released their third album We Need Medicine in 2013. Debuting at number twenty-six on the UK Albums Chart, it was considered a disappointment and marked significant decline in popularity for the band. We Need Medicine dropped out of the UK Top 100 after just one week. The album peaked at number one hundred and six on the US Billboard 200. Chart performances improved for the band with the release of their further releases, Eyes Wide, Tongue Tied (2015), In Your Own Sweet Time (2018) and Half Drunk Under a Full Moon (2021), all of which debuted within the top five in their native Scotland.

In addition to his work with both bands, Lawler has also released as a solo artist, releasing his debut album Psycho Jukebox in 2011, followed by his second solo studio album Bright Night Flowers in 2019.