James Robert Lamar (March 28, 1866 – August 11, 1923) was a U.S. Representative from Missouri.

He served as chairman of the Democratic congressional committee of the Thirteenth District of Missouri in 1894–1896.

He engaged in the practice of law in Houston, Missouri.

He resumed the practice of law in Houston, Missouri.

He served as president of the Missouri Bar Association in 1920.