McFly are a British pop rock band formed in London in 2003. The band took their name from the Back to the Future character Marty McFly. The band consists of Tom Fletcher (lead vocals, guitar, and piano), Danny Jones (lead vocals, harmonica, and guitar), Dougie Poynter (bass guitar, vocals) and Harry Judd (drums). They were signed to Island Records from their 2004 launch until December 2007, before creating their own label, Super Records.

McFly rose to fame after fellow band Busted, with whom they later formed McBusted, helped launch them by inviting them to tour in 2004. In 2005, they won the Brit Award for Best British Pop Act. McFly's debut album, Room on the 3rd Floor, debuted at number one on the UK Albums Chart and is certified as double platinum; this led to them taking the record, in the Guinness Book of Records, as being the youngest band ever to have an album debut at number one—a title taken from the Beatles. A month after the album was released, the band had their first UK headlining tour.

The band's second album, Wonderland, which was released in 2005, also charted at number one in the UK making them the youngest band to have topped the UK Albums Chart twice. Their third album, Motion in the Ocean, was released on 6 November 2006 and charted at number 6 in the UK. McFly released their All the Greatest Hits compilation album on 5 November 2007, which charted at number 4 in the UK. The band's fourth studio album, Radio:Active, was given away for free as a supplement in the Mail on Sunday on 20 July 2008, before being released in the conventional manner (via physical release) on 2 September 2008. Their fifth album, Above the Noise, was released in November 2010 and charted at number 20.

In November 2013, it was announced that McFly would be joining forces with Busted to form the "supergroup" McBusted. They played a 34-date tour with both Busted and McFly songs. The only member of the original groups not to participate in the new line-up was former Busted singer Charlie Simpson. After Simpson's return to Busted in November 2015, McFly made a return and sold out their Anthology Tour in September 2016. After that, the band took an indefinite hiatus, with their Twitter account confirming that the boys were focusing on solo projects in 2018. In January 2019, Poynter confirmed via a podcast that the band would be reforming that year with a new album and tour. In September the band announced a new album of previously unreleased material and a concert at the O2 Arena in November 2019, followed by a 2020 come-back arena tour, this would however be delayed to 2021 due to the COVID-19 pandemic. Their sixth album, Young Dumb Thrills, was released in 2020.

According to the British Phonographic Industry (BPI), McFly has been certified for 2 million albums and 3.6 million singles in the UK. and more than 10 million records worldwide. As of 2016, McFly have had 18 consecutive UK top 20 singles, seven of which reached number one in the UK Singles Chart and fifteen of which were consecutive top ten singles.

In 2001, Tom Fletcher auditioned for Busted, but lost out on the place to Charlie Simpson. Fletcher was originally accepted as part of Busted's line-up, but Island Records went on to reassess the situation and eventually decided to have the band as a three-piece rather than a four-piece. Though the record label decided against offering Fletcher a place in Busted, they were intrigued by his songwriting talents and later offered him a place on Busted's songwriting 'team', alongside band member (and already accomplished songwriter) James Bourne, whom Fletcher credits with helping him to compose melodies.

While writing Busted's second album, A Present for Everyone, Fletcher was asked by the record label if he was available to film auditions for a new band, V. It was at this time that Jones and Fletcher met for the first time; Danny Jones went to the audition mistaking the band to be an instrumental band rather than the conventional, all-singing, all-dancing boyband, for which they were intended. Fletcher was impressed with Jones' unique style and so approached and invited him to write with himself and Bourne. When writing projects for Busted had come to an end, the two began collaborating for their own (yet unnamed) band and, eventually, moved into the InterContinental Hotel in London for two months, (while still receiving help from Bourne) to concentrate on writing together. Bassist Dougie Poynter and drummer Harry Judd were subsequently recruited via a classified advertisement in the NME magazine. The pair, both from Essex, coincidentally turned up at the same audition and discussed their shared appreciation of the band the Starting Line, after Poynter noticed their name and logo was printed on Judd's T-shirt.

McFly's early sound was surf/pop rock. Their debut single, "5 Colours in Her Hair", released 29 March 2004, entered the UK Singles Chart at number 1 in April 2004 and stayed there the following week. In July 2004 their second single, "Obviously", also topped the charts. This was followed by the album Room on the 3rd Floor debuting at number 1 in the UK Albums Chart. It would go on to be certified double platinum by the British Phonographic Industry. The album broke records, as McFly earned an award from Guinness World Records for being the youngest band to have a debut album enter the charts in the top position, a distinction previously held by The Beatles. The idea for the album name came from where Jones and Fletcher wrote most of the songs for the album: room 363 in the InterContinental Hotel in London. The third single, "That Girl", was released on 6 September 2004, placing at number 3. The fourth single, Room on the 3rd Floor, the album's title track, was released on 15 November 2004 and reached number 5. McFly supported Busted on their nationwide arena tour along with V in February 2004 and then had their first headlining tour in September 2004.