"When We Collide" is a song by Matt Cardle, the winner of the seventh series of The X Factor. It is a cover of "Many of Horror" an alternative rock song written by Simon Neil of Scottish band Biffy Clyro.
Matt Cardle, recorded a studio version of the song under the title "When We Collide" and released it as his debut single, after having performed it in the final of the competition. It was made available as a digital download on 12 December 2010 shortly after the show had ended. A physical CD single was released on 15 December 2010. Biffy Clyro fans launched an internet campaign to get the original track "Many of Horror" to the festive charts, with fans joining a Facebook campaign urging people to buy Biffy Clyro's original single rather than Cardle's cover version. This resulted in the Biffy Clyro version reaching number 8 in the UK Singles Chart, its highest position ever, and Cardle's version became the UK Christmas number 1.
On 16 December 2010, "When We Collide" debuted at number one on the Irish Singles Chart, where it stayed for five weeks. It has since become the fourth best-selling song in the history of the chart. On 19 December, it charted number one in the UK Singles Chart, beating "What's My Name?" by Rihanna featuring Drake, and "Surfin' Bird" by The Trashmen, whilst the Biffy Clyro original of "Many of Horror" re-entered the chart at number eight. With sales of 815,000, it was the second best-selling single of 2010; the number one being "Love the Way You Lie" by Eminem featuring Rihanna, which sold 854,000 copies during 2010. As of June 2012, it had sold 1,000,167 copies, making it the 123rd single to sell a million copies in the UK, and the fourth by an X Factor contestant, after Shayne Ward's "That's My Goal", Leona Lewis's "Bleeding Love" and Alexandra Burke's "Hallelujah". According to the Official Charts Company, "When We Collide" is the 124th best selling song of all time in the UK.