The surname Ó Scannail (English: Scannell) is both an ancient Irish name and a clan who were a sept of the Eóganachta.
[1] The name derives from the Irish word scannal, originally meaning quarrel, contention, fight, or dispute.
One sept is O'Scannlain of Munster and the other is MacScannlain of Oriel, County Louth, neither of which has retained the prefix 0 or Mac in modern times.
[9] One of the earliest recorded written spellings of the family name is thought to be that of Máel Patraic Ua Scannail (also called Patrick O'Scannell), and dated 1262 - 1272, when he was Bishop of Raphoe and afterwards of Armagh.
By tradition the dynasty was founded by Conall Corc but named after his ancestor Éogan, the firstborn son of the semi-mythological 3rd-century king Ailill Aulom.