Dafydd Ddu o Hiraddug (died 1371), also known as Dafydd Ddu Athro o Hiraddug, was a Welsh language poet, grammarian, and cleric in the diocese of Llanelwy (St Asaph). He was once believed to be the son of a certain Hywel ap Madog of Tremeirchion, but this has now been disproven.