Harry Styles, Zayn Malik, Liam Payne, Louis Tomlinson and Niall Horan were complete strangers when they were eliminated from the "Boys" category of UK X Factor
in 2010 after reaching the bootcamp stage.
Guest judge Nicole Scherzinger realised there was far too much marketable teen boy going to waste, and had the stroke of genius to put them through to the next phase of the competition as a group. They ended up coming third on the show, but have become the most successful artists from the series by far.