William Marsey

William Marsey (born 29 September 1989) is a British composer. He studied music at the University of Cambridge and composition at the Royal Academy of Music, where he was Manson Fellow. He is also one of three artistic directors of Listenpony, a London-based concert series, record label and commissioning body.

Marsey's piece Belmont Chill (from Dutch Indoor Subjects) for solo piano was nominated for the British Composer Awards in 2018. He also composed music for Hofesh Shechter's East Wall in the same year.

Marsey received an Ivor Novello Award nomination at The Ivors Classical Awards 2023. Why Do You Grieve, for chamber ensemble, was nominated for Best Chamber Ensemble Composition.