William James Glackens (March 13, 1870 – May 22, 1938) is an American realist painter and one of the founders of the Ashcan School of American art.

He is also known for his work in helping Albert C. Barnes to acquire the European paintings that form the nucleus of the famed Barnes Foundation in Philadelphia.

His dark-hued, vibrantly painted street scenes and depictions of daily life in pre-Great War New York and Paris first establish his reputation as a major artist.

His later work is brighter in tone and shows the strong influence of Renoir.

During much of his career as a painter, Glackens also workaas an illustrator for newspapers and magazines in Philadelphia and New York City.