Charles Carstairs (August 1865 - July 1928) was an American art dealer. Throughout his career, Carstairs encouraged American clients to invest in European Old Master paintings. He worked closely with industrial magnate Henry Clay Frick, and was responsible for Frick's acquisition of the 'Ilchester Rembrandt' in 1906. Carstairs also worked with Joseph Widener, an American art collector and founding benefactor of National Gallery of Art in Washington, D.C.