Daniel D. Pratt (October 26, 1813 - June 17, 1877) was a United States Senator from Indiana. Born in Palermo, Maine, he moved to New York with his parents, who settled in Fenner. He attended the public schools and Cazenovia Seminary, and graduated from Hamilton College in 1831. He moved to Indiana in 1832 and taught school; in 1834 he settled in Indianapolis and was employed in the office of the Secretary of State. He studied law and was admitted to the bar, commencing practice in Logansport in 1836.
In 1851 and 1853 he was a member of the Indiana House of Representatives and was elected in 1868 as a Republican to the Forty-first Congress but resigned January 27, 1869, before the beginning of his term as a U.S. Representative, having been elected to the U.S. Senate. He was a member of the Senate from March 4, 1869, to March 3, 1875; while in the Senate he was chairman of the Committee on Pensions (Forty-second and Forty-third Congresses).
Pratt was appointed by President Ulysses Grant as Commissioner of Internal Revenue, holding that office in 1875 and 1876. He died in Logansport in 1877; interment was in Mount Hope Cemetery.