The mathematician Simon Norton passed away suddenly on 14 February. Norton attended Eton College and while still at school showed his prodigious talent for mathematics by obtaining an external first-class degree in Pure Mathematics from the University of London. He also represented the United Kingdom with distinction at the International Mathematical Olympiad, three years in succession. Norton spent most of his career at Cambridge and was one of the authors of the ATLAS of Finite Groups along with John Conway, Robert Curtis, Richard Parker and Robert Wilson. He was a ‘leading expert on the so-called Monster group, the largest of the sporadic simple groups, which describes symmetries in 196883-dimensional space, and an authority on Monstrous Moonshine, the remarkable connection between this group and modular functions’.