John Greenwood (1727–1792) was an early American portrait painter and engraver.
Greenwood was born in Boston, Massachusetts in 1727. He apprenticed with Thomas Johnston, a sign painter and engraver from 1742 to 1745 where he copied various English works. Besides portraits, Greenwood painted many satirical works. He left Boston in 1752 and went first to the Dutch colony of Surinam and then to Paris and England.
One of Greenwood's best known works is Sea Captains Carousing in Surinam (1755), a drunken scene featuring various prominent Rhode Island merchants, including Declaration of Independence signatory Stephen Hopkins, Governor Joseph Wanton, Admiral Esek Hopkins, and Governor Nicholas Cooke.
Greenwood died in London, England in 1792.