Derivation from the Irish Gaelic Mac Cú Uladh 'son of the hound of Ulster' is more probable. While Cú Uladh may allude to the legendary Irish figure Cú Chulainn, it was a common given name in medieval Ireland.
The name Mac Cú Uladh, which translates to "son of the hound of Ulster," is more likely the origin of this name. Although Cú Chulainn might be associated with the legend, it was a frequent name used in medieval Ireland.