Ó Flaithbheartaigh was an Irish clan based most prominently in what is today County Galway. The clan name originated in the 10th century as a derivative of its founder Flaithbheartach mac Eimhin. The surname O'Flaherty is the Anglicised form of the Gaelic name Ó Flaithbheartaigh. The name "Flaithbheartach" comes from the old Gaelic elements "flaith(eamh)" - meaning ''prince, ruler" 
"Ó" ('oh') is a Gaelic prefix used to mark out that the person in question is male (for females, 'Ní' was used). Of course, this does not mean that Oritz is male, as the practise has been dropped over the years.
- Pottermore (Mentioned only)