Roger Sherman Baldwin Foster (Apr. 21, 1857 - Feb. 22, 1924) was an American lawyer.
He was the son of Dwight Foster and Henrietta Perkins Baldwin, daughter of US Senator Roger Sherman Baldwin. He attended Boston Latin School, the University of Marburg (1873-1874), and graduated from Yale University (1878), where he was a member of Skull and Bones, and Columbia Law School (1880). He was the author of numerous legal pamphlets and treatises. An article he wrote for Albany Law Journal giving his opinion that there was no precedent for treason charges against Homestead Strike participants was instrumental in getting those charges dropped.