Lot Myrick Morrill (May 13, 1813–January 10, 1883) was an American statesman who served as Governor of Maine, and in the United States Senate and as Secretary of the Treasury.

He was born in Belgrade, Maine to Peaslee and Nancy (Macomber) Morrill, and studied law at Waterville College, now Colby College. His older brother Anson P. Morrill was also a prominent U.S. statesman.

A member of the Republican party, he served in the Maine State Senate from 1854 until 1856, and was elected Governor of Maine in 1858. (His brother Anson P. Morrill also served as Maine's governor.) He served in that office until 1861 when he was elected to the U.S. Senate to replace Hannibal Hamlin, who had left his seat to become Abraham Lincoln's running mate. He served in the Senate from 1861 until 1869 and then appointed to fill the vacancy caused by the death of William Pitt Fessenden and re-elected to the post, for another stint of service from 1869 to 1876. In the Senate he was the was the first chairman of the U.S. Senate Committee on Appropriations. He was also chairman of the U.S. Senate Committee to Audit and Control the Contingent Expense (38th and 39th Congresses ), U.S. Senate Committee on the District of Columbia (39th Congress), the Committee on Appropriations (40th , 41st , 43rd and 44th Congresses ) and the U.S. Senate Committee on the Library (41st and 42nd Congresses ).

He was then appointed Treasury Secretary and served from 1876 to 1877 under President Grant and for five days under Rutherford B. Hayes. Following his term in the Grant Administration, he returned to Maine and became Collector of Customs for the Port of Portland, Maine.

He died in Augusta, Maine, leaving his wife Charlotte and four daughters, and is interred at Forest Grove Cemetery in that city.