Joseph Spencer (October 3, 1714 – January 13, 1789) was an American lawyer, soldier, and statesman from Connecticut. During the Revolutionary War, he served both as a delegate to the Continental Congress and as a major general in the Continental Army.

Spencer was born in East Haddam, Connecticut. He was trained as a lawyer and practiced until 1753 when he became a judge. He was active in the militia, serving in King George's War and as a Lieutenant Colonel of the Middlesex militia in the French and Indian War.

By the time the American Revolution began, Spencer had advanced to Brigadier General of Connecticut’s militia, and in April 1775 he led them to support the Siege of Boston as the 2nd Connecticut Regiment. In June, when these units were adopted into the national army, he was made a brigadier general in the Continental Army.

In 1776 Spencer was promoted to major general in support of William Heath in the Eastern Department. The following year his military career became difficult. He cancelled a planned attack on British forces in Rhode Island and was censured by the Continental Congress. He demanded a court of inquiry and was exonerated, but when the controversy was resolved, he resigned his commission on June 14, 1778.

Spencer first served on the Connecticut Council (or state senate) in 1776. Free of military responsibility, the state sent him as a delegate to the Continental Congress in 1779. In 1780 he was returned to the council, and served there until his death.

Twice married, Spencer had sixteen children. He died in East Haddam and was buried in the Nathan Hale Park of East Haddam.