Mac Beatha
Mac BEATHA, Mac BEATHADH—IV—M'Beagh, MacBeath, MacBeth, MacBeith, MacBey, MacBay; 'son of Macbeth'; a Scottish form of Mac an Bheatha, which see; the name of a Scottish family who were hereditary physicians in Islay and Mull, and also historians to the Macleans. Some of them settled in Ulster.
Alphabetical Index to Irish Surnames