Ó Tuathaláin
Ó TUATHALÁIN—I—O Twohillane, O Towlane, O Toolane, O Tolane, Toulhan, Toolan, Toland, Tolan, Tolin, Toolis, Thulis; 'descendant of Tuathalán' (diminutive of Tuathal, people-mighty); the name of an Ulster family who were originally seated in Inishowen, Co. Donegal. A branch of the family migrated, in the 17th century, with the O'Donnells to Co. Mayo where they still flourish, but strangely anglicise their name Toolis and Thulis.
Alphabetical Index to Irish Surnames