Wilhelm Nero Pilate Barbellion was the nom-de-plume of Bruce Frederick Cummings (7 September 1889 – 22 October 1919), an English diarist who was responsible for The Journal of a Disappointed Man. Ronald Blythe called it "among the most moving diaries ever created".
Cummings was born in Barnstaple in 1889. He was a naturalist at heart and ended up working at the British Museum's department of Natural History in London. Having begun his journal at the age of thirteen, Cummings continued to record his observations there — gradually moving from dry scientific notes to a more personal, literary style. His literary ambitions changed course in 1914 upon reading the journal of the Russian painter Marie Bashkirtseff, in whom he recognised a kindred spirit (see the 14 October 1914 entry of his Journal); in his 15 January 1915 entry he indicated that he intended to prepare his Journal for publication: "Then all in God’s good time I intend getting a volume ready for publication."