Music's 30 Fiercest Feuds and Beefs

From classic-rock squabbles to hip-hop diss tracks and social media wars, here are the ridiculous, rancorous conflicts that have held us rapt We count down the 30 biggest feuds in rock and pop history from Paul McCartney vs. John Lennon to Katy Perry vs. Taylor Swift. Creative differences, financial disputes, drug abuse, love triangles - in the music industry, the opportunities to butt heads are basically limitless.