John Marshall Harlan was an American lawyer and politician who served as an associate justice of the Supreme Court of the United States from 1877 until his death in 1911. He is often called "The Great Dissenter" due to his many dissents in cases that restricted civil liberties, including the Civil Rights Cases, Plessy v. Ferguson, and Giles v. Harris. Many of Harlan's views expressed in his notable dissents would become the official view of the Supreme Court starting from the 1950s Warren Court and onward.

An associate justice of the Supreme Court of the United States is a justice of the Supreme Court of the United States, other than the chief justice of the United States. The number of associate justices is eight, as set by the Judiciary Act of 1869.