6. Lady Gaga
Whether you think pop music has a place at Glastonbury or not it seems inevitable that Lady Gaga will one day headline. Kylie Minogue was meant to play in 2005 before her unfortunate illness and Beyonce headlined in 2011 so it would not be out of the ordinary for an act like Gaga to be booked. She is certainly big enough to headline and is probably the biggest current artist on this list. Lady Gaga's 2011 album Born This Way went to the top of charts across the globe and she already has four UK No.1 singles despite only being around since 2008. Her albums have sold 25+ Million copies around the world and she has sold roughly 7.5 million singles in the UK alone. Lady Gaga's current Born This Way Ball Tour is likely to finish in March and she is likely to release her third album by the end of the year. Lady Gaga does not appear to be a great fan of Festivals although she played at V, T and Glastonbury in 2009. It is probable that one of the larger world-wide festivals will book her soon enough to headline though, especially with the current increase of large Pop acts at festivals.