Aeddan ap Blegywryd

Aeddan ap Blegywryd (died 1018) was a King of Gwynedd in medieval Wales. He became ruler in 1005 but the circumstances of his accession are unclear as he does not seem to have been closely related to his predecessor, Cynan ap Hywel. Aeddan ap Blegywryd was defeated in battle in 1018 and was killed, along with his four sons.

Idwal ap Meurig had been dispossessed of his lands in Gwynedd but recovered them in 993. However, in 1000, Aeddan ap Blegywryd wrested control of the whole of North Wales and Idwal's son, Iago, fled to Ireland.

At this time, Cynan ap Hywel was a King of Gwynedd, one of the kingdoms or principalities of medieval Wales, ruling from 999 to 1005. After he died in 1005, the throne of Gwynedd fell to Aeddan ap Blegywryd, who was apparently out of the direct line of succession. It is not known whether or not Aeddan seized the throne by force, but his lack of connection to the ruling family of Gwynedd suggests that he did.