Powell
Powell—The name is the anglicised form of Guilfoyle and Gilfoyle (Mac Giolla-Phóil) in the districts about Tulla. The name Powell itself is Welsh, from Ap' Howell, another form being Hoyle.
Alphabetical Index of Anglicised Surnames in Ireland
See also Woulfe’s Irish Names and Surnames
… and O'Hart's Irish Pedigrees