John Thomas (1724 – June 2, 1776) is an American doctor and soldier from Massachusetts who becomes a major general in the Continental Army.

He is a leader during the siege of Boston.

Thomas briefly commands the withdrawal from Canada after the unsuccessful invasion by the Continental Army.

He dies from smallpox during the retreat.

Thomas was born in Marshfield, Massachusetts.

As a young man he studied medicine with Doctor Tufts in Medford before beginning his own practice in Kingston.

He was married to Hannah Thomas with whom he had two sons and a daughter.