Donnchad Ua Cerbaill or Donnchadh Ó Cearbhaill, king of Airgíalla, fl. 1130s-1168.
Ua Cerbaill was a supporter of the Irish religious reform movement of the 11th century. He was a close associate of Saint Malachy, and with him founded Mellifont Abbey. He was also responsible for foundations by the Arrouaisian order at Louth, Knock and Termonfeckin. He conquered and incorporated the Ulaid sub-kingdom of Conaille Muirtheimne, which formed the basis of modern County Louth, into his kingdom. He was responsible for the successful overthrow of Muirchertach Mac Lochlainn, High King of Ireland, who had blinded his foster-son the king of Ulaid. Afterwards he placed Áed in Macáem Tóinlesc on the throne of Tír Eogain.
He was a half-brother of Tigernán Ua Ruairc.