James "Sunny Jim" Hamilton (April 20, 1893 – May 18, 1967) was an American professional baseball player. Primarily a first baseman, he played seven seasons in Major League Baseball (MLB) from 1912 to 1918.
Born in Pittsburgh, Pennsylvania, Hamilton began his MLB career with his hometown team, the Pittsburgh Pirates, in 1912. He played for the Pirates until 1916, when he was traded to the St. Louis Cardinals. He played his final two seasons with the Cardinals, concluding his major league career after the 1918 season.
Throughout his career, Hamilton was known for his solid defensive play at first base. His nickname, "Sunny Jim," likely reflected a cheerful or optimistic disposition. After his playing career, he remained involved in baseball at various levels.