William Merchant Richardson (January 4, 1774 – March 15, 1838) was a member of the U.S. House of Representatives from Massachusetts and chief justice of the New Hampshire Supreme Court.

He graduated from Harvard University in 1797; studied law; was admitted to the bar and commenced practice in Groton, Massachusetts, in 1804.

He was elected as a Democratic-Republican to the Twelfth Congress to fill the vacancy caused by the resignation of Joseph B. Varnum; and was reelected to the Thirteenth Congress and served from November 4, 1811, to April 18, 1814, when he resigned.

[1] He is the author of The New-Hampshire Justice of the Peace (Concord, 1824) and The Town Officer (1824) and was co-reporter of the New Hampshire Superior Court Cases, of which the reports of several volumes are his alone (11 vols., 1819–'44).

He was the father of Anne, grandfather of sculptor Daniel Chester French, and uncle of William Adams Richardson who was United States Secretary of the Treasury from 1873 to 1874.