Samuel Irving Rosenman (February 13, 1896 – June 24, 1973) was an American lawyer, judge, Democratic Party activist, and presidential speechwriter. He coined the term "New Deal", and helped articulate liberal policies during the heyday of the New Deal coalition. He was the first person to hold the position of White House Counsel.

Rosenman was born in San Antonio, Texas, the son of Solomon and Ethel (Paler) Rosenman, both Jews. He served in the US Army during World War I and graduated from Columbia Law School in 1919. He was a member of Phi Beta Kappa and Delta Sigma Rho.

He became active in Democratic politics and was a member of the New York State Assembly (New York Co., 11th D.) in 1922, 1923, 1924, 1925 and 1926; and a justice of the New York Supreme Court (1st D.) from 1936 to 1943. By the mid-1930s, Rosenman had emerged as a leading spokesman for the New York Jewish community.

Rosenman was a senior advisor to presidents Franklin Roosevelt and Harry Truman. Under their administrations, he was a leading figure in the war crimes issue. He was also the first official White House Counsel, then called Special Counsel, between 1943 and 1946.

He was a speechwriter under both presidents, helping Roosevelt with his speeches from his days as governor. Rosenman was responsible for the term "New Deal", a phrase in the conclusion of FDR's acceptance speech at the 1932 Democratic National Convention. While he was not heavily involved in speechwriting during Roosevelt's first term, he started traveling to Washington to help out with important talks during the 1936 campaign and was a key speech aide for the remainder of Roosevelt's life. He officially joined the White House after ill health forced him to have to choose between his judicial work and his presidential work.

Beginning in 1940, Rosenman was frequently engaged by F.D.R. to assist in the reorganization of Government agencies to create greater efficiency in war mobilization. He coordinated the meetings and discussions that led to the reorganization of agencies overseeing production of war materials, allocation of resources, housing, control of inflation and other domestic concerns critical to the war effort.

He submitted his resignation as Special Counsel upon Roosevelt's death but Truman asked him to stay on, initially through V-E Day, then through V-J Day, and finally into 1946. Rosenman wrote the 1946 State of the Union Address for Truman on his own in 1946. Even after leaving the White House, he would periodically return to aid President Truman with major speeches, including his acceptance speech to the 1948 Democratic National Convention.

Rosenman's memoir, Working with Roosevelt, is one of the most quoted and praised first-person accounts of the Roosevelt administration.