Frank O. Briggs (August 12, 1851 - May 8, 1913) was a United States Senator from New Jersey. Born in Concord, New Hampshire, he attended the public schools, Francestown Academy, and Phillips Academy; he graduated from the United States Military Academy in 1872 and served in the Second Regiment, United States Infantry, as second lieutenant until 1877, when he resigned from the Army. In 1877, he moved to Trenton, New Jersey and engaged in the manufacture of wire and wire products; he was a member of the Trenton School Board from 1884 to 1892 and was mayor of Trenton from 1899 to 1902. In 1901 and 1902, he was a member of the State board of education, and was State treasurer from 1902 to 1907.
Briggs was chairman of the Republican State committee from 1904 to 1911 and was elected as a Republican to the U.S. Senate, serving from March 4, 1907, to March 3, 1913; he was an unsuccessful candidate for reelection. While in the Senate, he was chairman of the Committee on Geological Survey (Sixty-first Congress) and a member of the Committee to Audit and Control the Contingent Expense (Sixty-second Congress). He resumed his former business pursuits in Trenton, where he died in 1913; interment was in Riverview Cemetery.
Frank O. Briggs' father, James Frankland Briggs, had been a U.S. Representative from New Hampshire from 1877 to 1883.