&Collide& is a song by British recording artist Leona Lewis and Swedish DJ and record producer Avicii. It was written by Tim Berg, Simon Jeffes, Arash Pournouri, Autumn Rowe, Sandy Wilhelm, with production helmed by Wilhelm under his production name Sandy Vee and The Young Boys. &Collide& is a house inspired love song, that's instrumentation consists of piano riffs and a guitar. The song was recorded for Lewis' third studio album Glassheart, but was not included on the album's final track listing.

Upon the release of the single, Avicii claimed that Lewis and her record label, Syco, had sampled his song &Penguin& without his authorisation, and accused them of plagiarism. Before the lawsuit was filed by Avicii and his record label reach the high court, Syco announced that the song would be a joint release between Lewis and Avicii. The song premiered in the United Kingdom on 15 July 2011 and was sent to Australian radio on 22 August 2011. &Collide& was released digitally via the iTunes Store on 2 September, as part of a collection of the original song, as well as remixes by Afrojack, Cahill, Alex Gaudino and Jason Rooney. The Afrojack remix is included as a bonus track on the deluxe edition of Glassheart.

&Collide& received a mixed reaction from music critics. Some were complimentary of Lewis's vocal performance and compared it to Katy Perry's song &Firework&, whilst others were critical of its musical structure. The song achieved commercial success, and peaked inside the top five of the singles charts in Ireland, Scotland and the United Kingdom. It also peaked at number one on the US Hot Dance Club Songs chart. As part of promotion for the song, an accompanying music video was shot on a beach in Malibu, California and directed by Ethan Ladder. Lewis also performed the song on the game show Red or Black? and at London nightclub G-A-Y, along with other songs. At the 2012 Grammy Awards, the Afrojack remix was nominated for Best Remixed Recording.