Potter Stewart (January 23, 1915 - December 7, 1985) was an Associate Justice of the United States Supreme Court.

Stewart was born in Jackson, Michigan while his family was on vacation. His father, James G. Stewart , was a prominent Republican from Cincinnati, Ohio. His father served as Mayor of Cincinnati for seven years and was later a judge on the Ohio Supreme Court.

Stewart attended the Hotchkiss School, graduating in 1933. Then, he went on to Yale University, where he graduated in 1937. Here he was elected to Phi Beta Kappa and served as chairman of the student newspaper, The Yale Daily News. He graduated from Yale Law School in 1941, where he was an editor of the Yale Law Journal. At Yale, he was a member of Phi Delta Phi fraternity. Other members of that era included Gerald R. Ford, Peter H. Dominick , Walter Lord, William Scranton, R. Sargent Shriver, Cyrus R. Vance, and Byron R. White.

He served in World War II as a member of the US Naval Reserve aboard oil tankers.

In 1943, he married Mary Ann Bertles in a ceremony at Bruton Episcopal Church in Williamsburg, Virginia. His brother, Zeph Stewart (an initiate of Skull and Bones), was the best man. They eventually had a daughter, Harriet (Virkstis), and two sons, Potter, Jr. and David.

At the age of 39, in 1954, he was appointed to the United States Court of Appeals for the Sixth Circuit. In 1958, President Eisenhower nominated Stewart to the Supreme Court to replace Justice Harold Hitz Burton, who was retiring.

Stewart retained a moderate outlook throughout his tenure on the Court, perhaps best typified by his joining the decision in Furman v. Georgia (1972) which invalidated all death penalty laws then in force, and then joining in the Court's decision four years, Gregg v. Georgia, which upheld the revised capital punishment legislation adopted in a majority of the states. Stewart dissented from the Court's decision in Griswold v. Connecticut (1965), invalidating a law banning the sale of contraceptives based on a "Right of Privacy," arguing that such a right did not exist, but changed his views and was a key mover behind the Court's decision in Roe v. Wade (1973), which recognized the right to abortion under the "Right of Privacy." Stewart wrote a concurrence in that case, accepting the right recognized in Griswold.

To the lay public, Stewart may be best known for a quotation, or a fragment thereof, from his opinion in the obscenity case of Jacobellis v. Ohio (1964). Stewart wrote in his short concurrence that obscenity was hard to define, but that "I know it when I see it[.]" Usually dropped from the quote is the remainder of that sentence, "and the motion picture involved in this case is not that."

Stewart remained on the Court until his retirement in July 1981 at the age of 66.

After his retirement, he appeared in a series of public television specials about the United States Constitution with Fred W. Friendly.