Ó hEóluis
Ó hEÓLUIS, Ó hEÓLUSA—I—Olus; 'descendant of Eolus' (knowledge); the name of a Leitrim family who were anciently chiefs of Muinntear Eoluis, in that county. They afterwards changed their name to Mac Raghnaill, which see. O'Donovan, however, writes: "This family name is still in use and anglicised Olus." It must be extremely rare.
Alphabetical Index to Irish Surnames