Daniel Clark (October 24, 1809 – January 2, 1891) was a United States senator from New Hampshire and a United States district judge of the United States District Court for the District of New Hampshire.

Born on October 24, 1809, in Stratham, New Hampshire,^[1] Clark attended the common schools Hampton Academy (now New Hampton School) and Union College in Schenectady, New York.^[2] He graduated from Dartmouth College in 1834 and read law in 1836.^[1] He was admitted to the bar and entered private practice in Epping, New Hampshire from 1836 to 1839.^[1] He continued private practice in Manchester, New Hampshire from 1839 to 1842, 1844 to 1846, and from 1847 to 1861.^[1] He was a member of the New Hampshire House of Representatives from 1842 to 1843, in 1846, and from 1854 to 1855.^[1]

Clark was elected as a Republican to the United States Senate to fill the vacancy caused by the death of United States Senator James Bell.^[2] He was reelected in 1861, and served from June 27, 1857, to July 27, 1866, when he resigned to accept a federal judicial post.^[2] He served as President pro tempore of the United States Senate during the 38th United States Congress.^[2] He was Chairman of the United States Senate Committee on Claims for the 37th through the 39th United States Congress.^[2]

Clark was nominated by President Andrew Johnson on July 27, 1866, to a seat on the United States District Court for the District of New Hampshire vacated by Judge Matthew Harvey.^[1] He was confirmed by the United States Senate on July 27, 1866, and received his commission the same day.^[1] His service terminated on January 2, 1891, due to his death in Manchester.^[1]