Charles O'Neill (31 August 1882 – 9 September 1964) was a Canadian bandmaster, composer, organist, cornetist, and music educator of Scottish birth and Irish parentage. Although he wrote many symphonic and choral works, the majority of his compositional output was devoted to band music.
Born in to Irish parents, O'Neill began his musical training in the piano as a young child. He then studied the organ with Albert Lister Peace in Glasgow and music theory with Archibald Evans in London. From 1897 to 1901 he serves as organist at Grimsby, Lincolnshire and was a cornet player in a local band in that city.
In 1901 O'Neill crossed the Atlantic Ocean to settle in Boston, Massachusetts in the United States. He relocated to New York City in 1903 and then moved again in 1905 to Kingston, Ontario in Canada. In Kingston he played in the Royal Canadian Horse Artillery Band as a cornet soloist. In 1908 he returned to England to receive training as a bandmaster for at the Royal Military School of Music at Kneller Hall through the support of the Canadian Department of National Defence.
After earning a diploma from the RMSM in 1909, O'Neill returned to Canada in 1910 to succeed Joseph Vézina in the post of music director of the Royal Canadian Garrison Artillery Band at the Citadelle of Quebec. He obtained the rank of captain in 1919. While directing the band he pursued further studies in music composition and theory with Herbert Sanders in Ottawa and then entered the music program at McGill University. He earned a Bachelor of Music degree from McGill in 1914, making him one of the first students to earm such a degree from the school. Ten years later he earned a Doctor of Music from McGill with an emphasis in composition. He composed his largest work, the cantata The Ancient Mariner for chorus and orchestra, for his doctoral exercise.