Henry Darnall III (c. 1702-c. 1783) was a wealthy planter in Colonial Maryland. He was the son of the politician and planter Henry Darnall II, and the grandson of Henry Darnall who was the Proprietary Agent of Charles Calvert, 3rd Baron Baltimore (1605–1675), and served for a time as Deputy Governor of the Province. Henry Darnall III converted to Anglicanism and entered politics at a time when the Calvert family had regained their proprietary colony, having lost it during the Protestant Revolution of 1689. Darnall received much criticism for his faith and was accused of being a secret Catholic. Worse, in 1761 he was accused of embezzling almost £1,000 thanks to his position as Naval Officer of the colony, and was forced to flee Maryland for Europe in order to avoid being placed on trial.