William Avery Rockefeller, Sr. (November 13, 1810 – May 11, 1906) was the father of American oil tycoon and billionaire, John Davison Rockefeller (July 8, 1839 – May 23, 1937) and William Rockefeller (1841–1922), who both founded the Standard Oil company.

"Big Bill" was a quack doctor and a confidence trickster. An unreliable father, he played virtually no role in his son's business career, but he lived to a great age.

Rockefeller was born in Granger, New York to Godfrey Rockefeller (September 24, 1784, Albany, New York–September 28, 1857, Richford, New York) and Lucy Avery (February 11, 1786, Great Barrington, Massachusetts–April 6, 1867), married in 1806. He was one of 10 children:
Melinda Rockefeller (September 12, 1807–May 2, 1880), married to William Harris
Olymphia Rockefeller (April 20, 1809–)
William Avery Rockefeller, Sr.
Norman Rockefeller
Sally Ann Rockefeller
Jacob S. Rockefeller
Mary Rockefeller
Miles Avery Rockefeller
Mary Miranda Rockefeller
Egbert Rockefeller

The Rockefellers trace their family back to Goddard Rockenfeller (1590) of Fahr, today part of Neuwied, Germany. The first Rockefeller to settle in America was Johann Peter Rockefeller (1710, Segendorf, Neuwied; 1787, Amwell Township, New Jersey). Goddard Rockenfeller was reputedly a descendant of Augier de Roquefeuil, younger brother of Guillaume IV de Roquefeuil, the ancestor of later sires, and John (Jean) de Roquefeuil, the ancestor of the Roquefeuil-Versols Family of France, sons of Adhemar I de Roquefeuil, Sire of Versols (died 1477).[1]

Lucy Avery was daughter of Miles Avery and wife Malinda Pixley, and descended by her father from Edmund of Langley's first marriage (through 5th Baron Audley's second marriage)[2] and from Mary Boleyn's first marriage (through the 2nd Barons de la Warr)[3].

Rockefeller and his first wife, Eliza Davison Rockefeller (September 12, 1813–March 28, 1889), married in 1837, were the parents of six children:
Lucy Rockefeller Briggs (1838–1878), married to Pierson Briggs
John Davison Rockefeller
William Rockefeller
Mary Ann Rockefeller (1843–1925)
Francis Rockefeller (daughter) (1845–1847)
Franklin Rockefeller
Although he abandoned the family while John was a teenager, he remained married to Eliza until her death. In 1856, having assumed the name William Levingston, he married Margaret Allen (ca 1835–) in Norwich, Ontario, Canada, without issue. While still married to his first wife, he had two daughters by one Nancy Brown:
Clorinda Rockefeller (ca 1838–)
Cornelia Rockefeller (ca 1839–)

After hearing rumours that the richest man in the world — then at the height of his notoriety as a monopolist — had a shameful family secret, the press went into a frenzy. Joseph Pulitzer offered a reward of eight thousand dollars for information about "Doc Rockefeller" who was known to be alive and living under a false name, but whose whereabouts were a family secret. Despite slender clues picked up from interviews with family members and an eighteen month search, the journalists failed to track him down before he died, and the full story wasn't exposed until two years later.

William Rockefeller had spent sometime in Park River, North Dakota under the Levingston alias. He died on May 11, 1906, in Freeport, Illinois and was buried there in Oakland Cemetery. John Rockefeller never publicly acknowledged the truth about his father's life as a bigamist, and William's grave marker was paid for out of his second wife's estate.