William Pinhorne (died c. 1720) was an American colonial politician and jurist, who served in various capacities in both New York and New Jersey.
In 1691, with the accession of Governor Henry Sloughter, Pinhorne was appointed to the New York Provincial Council, where he served on the Committee for Preparing the Prosecution of Jacob Leisler.
He then served as a judge in a special session of the Court of Oyer and Terminer which convened to try Leisler on charges of treason.
In 1692 he moved to a plantation of over 1,000 acres (400 ha) at Snake Hill in East Jersey, which resulted in his suspension on September 1 from his positions for non-residence.
"[3] In 1698 William Pinhorne was appointed one of the East New Jersey Provincial Council during the administration of Governor Jeremiah Basse; he held the position up through the surrender of government to the Crown.
Unbeknownst to Ingoldesby, his own commission as lieutenant governor was revoked in October 1709, but the news only reached him in April 1710.