Thomas Lynch Jr. (August 5, 1749 - circa 1779) was an American planter and signer of the Declaration of Independence representing South Carolina. Born into a prominent family, he studied at Eton College and Cambridge University in England before returning to the colonies.

Lynch joined the Continental Congress in 1776, stepping in for his ill father, Thomas Lynch Sr. Both were appointed to Congress, a rare father-son pairing. After signing the Declaration, his health declined, and in 1779 he sailed to Europe seeking recovery. Tragically, his ship was lost at sea, and he was presumed dead at age 30.