Charles Lang Freer (1854 – 1919) was an American railroad-car manufacturer from Detroit, Michigan who gave to the United States his art collections and funds for a building to house them. The Freer Gallery of Art founded by him is part of the Smithsonian Institution in Washington, D.C.

Freer's business career started in the manufacture of railroad cars. With Frank J. Hecker, Freer formed (in 1885) the Peninsular Car Company, Detroit's second largest car manufacturer which eventually merged into American Car and Foundry.

Freer is perhaps the most important collector of the works of James Whistler. Freer is famous not only for being an industrialist and art collector, but also an avid writer. His personal communications (letters and telegrams) between himself and Whistler have been published and are legendary in the art community. He also shared decades-long communications between himself and other important American art collectors and patrons.

A few of these early patrons went on to establish collections similar in importance (if not necessarily volume) to that of Freer. See: The Phillips Collection, The Vess Collection, The Roosevelt Collection, and others.