William Sartain was an American artist.

Sartain was born in Philadelphia on November 21, 1843, and his father was John Sartain. His sister, Emily Sartain, was also an artist, and eventually became the director of the Philadelphia School of Design for Women.

He attended Central High School (Philadelphia) and the Pennsylvania Academy of the Fine Arts with artists Thomas Eakins and Charles Lewis Fussell. Eakins and Sartain traveled together in 1868. He stayed in Paris until 1875, when he returned to Philadelphia, and moved to New York City.

He died at Post Graduate Hospital on October 25, 1924.

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.