If the name McCullough derives from “mac cu Uladh,” meaning “son of the dog of Ulster,” then it prompts the question: “Who was Cu-Uldadh?” We have suggested the origin of this name may ultimately stem from Cú Chulainn of Irish mythology. But who else used this name historically?

The latter name appears to have been used as a forename by at least two kings of Ulster, including Cu-Uladh Ua Flaithri and Cu-Uladh Ua Duinnsleibhe Ui-Eochadha (described as the last McDunlevy king of Ulster).