William Sartain (November 21, 1843 – 1924) was an American artist.
Sartain was born in Philadelphia, and his father was John Sartain. His sister, Emily Sartain, was also an artist became the director of the Philadelphia School of Design for Women. He went to high school with Thomas Eakins; they traveled together in 1868. He studied at the Pennsylvania Academy of the Fine Arts. He stayed in Paris until 1875, when he returned to Philadelphia, and moved to New York City.
His work is in the Pennsylvania Academy of the Fine Arts, Philadelphia Museum of Art, Brooklyn Museum, U.S. Capitol, and National Museum of American Art.