Increase Sumner 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.

The governor of the Commonwealth of Massachusetts is the chief executive officer of the government of Massachusetts. The governor is the head of the state cabinet and the commander-in-chief of the commonwealth's military forces.