Sir Dafydd ap Llewelyn ap Hywel (c. 1380 – October 25, 1415), better known as Dafydd Gam or Davy Gam, was a Welsh medieval nobleman, a prominent opponent of Owain Glyndŵr, and who died at the Battle of Agincourt fighting for King Henry V, King of England in that victory against the French. The name "Gam" is taken from a Welsh word for "lame/deformed" (from which 'gammy', as in 'gammy leg', may be derived), and stories about him give him a characteristic squint which may have led to his nickname 'gam' . It is possible that he may have lost an eye. Regarded as a traitor ("Crooked David") by some Welshmen, he is regarded as a hero by others; his reputation has waxed and waned with those of his enemy Glyndŵr and his ally King Henry V.