William Cranch (July 17, 1769–September 1, 1855) was an American judge and the second reporter of decisions of the United States Supreme Court.

Born in Weymouth, Massachusetts, he was a nephew of Abigail Adams. At the time, the reporter was an unofficial post and he used his own funds to produce the reports. Cranch took on the responsibility because of his respect for precedent. He was slow in producing his reports of cases and their accuracy was questioned.

When a land speculation bankrupted him, his uncle John Adams rescued him by appointing him to be judge of the District of Columbia circuit court, where he served until his death. Cranch, like William Marbury , was one of the "midnight judges" appointed under the Judiciary Act of 1800 that led to the Supreme Court case Marbury v. Madison. During his tenure on the court, Cranch published a biography of Adams, and was a member of the Academy of Arts and Sciences .

He died in Washington, D.C..