| Birth Name: | Prentiss Marsh Brown |
| Birth Date: | 18 June 1889 |
| Birth Place: | St. Ignace, Michigan, U.S. |
| Death Place: | St. Ignace, Michigan, U.S. |
| Party: | Democratic |
| Alma Mater: | University of Illinois at Urbana-Champaign Albion College |
| State1: | Michigan |
| Jr/Sr1: | United States Senator |
| Term Start1: | November 19, 1936 |
| Term End1: | January 3, 1943 |
| Predecessor1: | James J. Couzens |
| Successor1: | Homer S. Ferguson |
| State2: | Michigan |
| District2: | 11th |
| Term Start2: | March 4, 1933 |
| Term End2: | November 18, 1936 |
| Predecessor2: | Frank P. Bohn |
| Successor2: | John F. Luecke |
| Office3: | Administrator of the Office of Price Administration |
| Term3: | 1943 |
| Restingplace: | Lakeside Cemetery |
| President3: | Franklin D. Roosevelt |
| Predecessor3: | Leon Henderson |
| Successor3: | Chester Bowles |
| Spouse: | Marion Walker |
| Children: | Prentiss M. Brown, Jr., Paul W. Brown, Jim Brown, four others |
Prentiss Marsh Brown (June 18, 1889December 19, 1973) was an American lawyer and politician who served three full and one partial term as a Democratic U.S. Representative and Senator from the state of Michigan from 1936 to 1943.
Brown was born in St. Ignace, Michigan and attended the public schools there. He attended the University of Illinois at Urbana-Champaign and graduated from Albion College in Albion, Michigan in 1911. He studied law and was admitted to the bar in 1914 and commenced practice in St. Ignace.
Brown married Marion Walker in 1916. The couple had a total of seven children.
Brown was prosecuting attorney of Mackinac County from 1914 to 1926 and the city attorney of St. Ignace from 1916 to 1928.
He was an unsuccessful candidate for election in 1924 to the United States House of Representatives and in 1928 for election as justice of the Michigan Supreme Court. He was a member of the State Board of Law Examiners from 1930 to 1942.
Brown was elected as a Democrat from Michigan's 11th congressional district to the United States House of Representatives for the 73rd Congress and was reelected to the 74th Congress, serving from March 4, 1933, until his resignation, effective November 18, 1936.
He was elected as a Democrat on November 3, 1936, to the United States Senate for the term beginning January 3, 1937, but was subsequently appointed to the United States Senate to fill the vacancy caused by the death of James Couzens for the term ending January 3, 1937. In total, he served from November 19, 1936, to January 3, 1943.
He was chairman of the U.S. Senate Committee on Claims in the Seventy-seventh Congress. He was also a member of the Banking and Currency Committee, and in this capacity was instrumental in helping Franklin D. Roosevelt achieve his desired wage and farm price controls. He was an unsuccessful candidate for re-election in 1942.
In December 1942, Roosevelt selected Brown to take over as administrator of the Office of Price Administration, replacing Leon Henderson, whose tenure as administrator was listed as one of the major reasons for Democratic losses in the 1942 elections. In 1943 he resumed the practice of law in both Washington, D.C., and Detroit, Michigan. He also served as chairman of the Detroit Edison Company.
In 1951, Brown was named chairman of the new Mackinac Bridge Authority and served until his death. During his chairmanship, this authority oversaw the construction of Michigan's Mackinac Bridge. He once stated during a radio interview that he came up with the idea for the Mackinac Bridge after an unusually bitter winter one day disrupted his commute to work by ferry and forced him to cross the strait on the brittle icy lake surface.
Brown died in St. Ignace at the age of 84 and is interred there at Lakeside Cemetery.
Two of Brown's children were also active in Democratic party politics. His son, Prentiss M. Brown, Jr., ran unsuccessfully for Congress several times, in 1952, 1956, 1958, and 1960, and was the city attorney for St. Ignace for 50 years. Paul Walker Brown was a member of the Board of Regents of the University of Michigan from 1971 until 1994, and ran unsuccessfully for lieutenant governor in 1974.