Mathieson, Matheson
Mathieson, Matheson—These two names are the anglicised forms of the Scottish clan name Mac Mhathan. Its earlier form was Mac Mathghamhna, similar to the Irish form of M'Mahon. Some of the clan still retain a lesser anglicised form in McMathan. Matthewson is another form assumed.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees