William Henry Herriman (7 February 1829 – 26 July 1918) was an expatriate American art collector in Rome who, on his death, left important works of art to the Metropolitan Museum of Art in New York and the Brooklyn Museum.
William Henry Herriman was the second son (and third child) of the wealthy Brooklyn businessman and President of Long Island Bank,William S. Herriman and his wife Maria Belle Stillwell Frecke/Freeke. William H. married Elizabeth Herriman née Wyckoff (23 April 1834 – 5 May 1910).
His sister was Caroline Herriman Polhemus (died 1906), the wife of Henry Ditmas Polhemus. After his death, she founded the Polhemus Memorial Clinic, the first "skyscraper hospital", in honour of her late husband, who had served as the Regent of Long Island College Hospital (LICH) from 1872 until his death in 1895. She also founded the Herriman Home in Monsey, Rockland County.
Herriman and his wife first lived in Brooklyn, New York, but moved to Rome in 1865. Their friend, Maitland Armstrong, said of them: "They exercised a quiet and generous hospitality in their delightful apartment, and were among the best friends the American artists had, for they bought their pictures, befriended them in their need, nursed them in sickness, and lent them money when they were hard up. Mr. Herriman was a wise collector, not only of pictures but of all sorts of rare objects of art."
Herriman left a large number of works to the Brooklyn Museum on his death, including Jean-François Millet's 1860s painting, Shepherd Tending His Flock. He left fewer works to the Metropolitan Museum of Art, but among those he did donate to them was one of the most important that he owned, Gustave Moreau's 1864 Oedipus and the Sphinx, one of the few Moreau paintings in private hands. On his death Moreau had left all of his extant paintings to the French nation where they formed the basis for the subsequent Gustave Moreau Museum. Accordingly, important Moreau paintings are scarce outside France. Herriman had purchased Oedipus and the Sphinx in 1868 during Moreau's lifetime and it was installed at 93, Piazza di Spagna, Rome, by January 1869.