Increase Sumner, American lawyer, jurist, and politician, 5th Governor of Massachusetts (d. 1799)
Increase Sumner (November 27, 1746 – June 7, 1799) was an American lawyer, jurist, and politician from Massachusetts. He was the fifth governor of Massachusetts, serving from 1797 to 1799. Trained as a lawyer, he served in the provisional government of Massachusetts during the American Revolutionary War, and was elected to the Confederation Congress in 1782. Appointed to the Massachusetts Supreme Judicial Court the same year, he served there as an associate justice until 1797.

He was elected governor of Massachusetts three times by wide margins, but died shortly after the start of his third term. His descendants include his son William H. Sumner, for whom the Sumner Tunnel in Boston, Massachusetts, is named, and 20th-century diplomats Sumner Welles and Sumner Gerard.