William McCullough

(male) Probably the most successful of all the Old French names of Germanic origin that were introduced to England by the Normans. It is derived from Germanic wil ‘will, desire’ + helm ‘helmet, protection’. The fact that it was borne by the Conqueror himself does not seem to have inhibited its favour with the ‘conquered’ population: in the first century after the Conquest it was the commonest male name of all, and not only among the Normans. In the later Middle Ages it was overtaken by John, but continued to run second to that name until the 20th century, when the picture became more fragmented.

Irish (especially Ulster): Anglicized form of the Gaelic surname Mac Cú Uladh, a patronymic from Cú Uladh ‘hound of Ulster’. Compare McNally, which is from Mac Con Uladh, genitive form of the same name. It has sometimes been erroneously associated with Gaelic cullach ‘wild boar’, and some families in County Sligo have translated it into English as Boar.