Ó Gruagáin
Ó GRUAGÁIN, Ó GRÚAGÁIN—I—O Growgane, O Grogaine, Groogan, Grogan, Groggan; 'descendant of Gru(a)gán' (diminutive of gruag, hair of the head, or of grúg, fierceness, anger); the name of a Roscommon family who were erenaghs of Elphin; now found in all parts of Ireland.
Alphabetical Index to Irish Surnames