Shannon
Shannon.—This name in Kintyre and the adjoining districts, and in North-East Ulster is the anglicised form of a sept of the McDonalds in Kintyre. It was earlier written O'Shanney. A Rev. Malcolm Mac-O'Shannon was minister of Kilcolmkill and Kilblaan, Kintyre, in 1630, correctly written O'Seanáinn. We find it anglicised M'Shannon in Co. Antrim.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees