Shellback

Shellback, born Karl Johan Schuster, is a Swedish songwriter and producer who came up as the most prominent of Max Martin's collaborators and is now a major pop architect in his own right. A former rock drummer, he met Martin in the early 2000s as a teenager and the two went on to dominate the charts together. His credit list is studded with era-defining pop: a long and central run with Taylor Swift, plus work for P!nk, Britney Spears, Avril Lavigne, Adam Lambert, Cher Lloyd, Katy Perry, Ariana Grande, Maroon 5 and Ed Sheeran. A writer as much as a producer, he has won four Grammy Awards. Across more than a thousand credits, his trademark has been the muscular, hook-forward pop-rock that bridged the gap between guitar music and the modern Hot 100.