William Avery Bishop, VC, CB, DSO & Bar, MC, DFC, ED (8 February 1894 – 11 September 1956) was a Canadian flying ace of the First World War.
He was officially credited with 72 victories, making him the top Canadian and British Empire ace of the war. He was an Air Marshal and a Victoria Cross recipient.
One day in July 1915, Bishop saw an airplane land in a nearby field and then take off again; this event would change the whole direction of his career.

"...It was the mud, I think, that made me take to flying… I had succeeded in getting myself mired to the knees when suddenly, from somewhere out of the storm, appeared a trim little aeroplane.
It landed hesitatingly in a near-by field as if scorning to brush its wings against so sordid a landscape; then away again up into the clean grey mists.
How long I stood there gazing into the distance I do not know, but when I turned to slog my way back through the mud my mind was made up. I knew there was only one place to be on such a day — up above the clouds in the summer sunshine".

William A. Bishop

Bishop discovered that it would be six months before he could be trained as a pilot, but if he became an observer, he could be admitted immediately. Bishop applied for a transfer to the Royal Flying Corps and became a RFC observer in September 1915. He was stationed with the No. 21 Squadron and went to the front lines in January 1916, where the Squadron flew missions deep into enemy territory. 
During the Second World War, Bishop was instrumental in setting up and promoting the British Commonwealth Air Training Plan.