William Oliver

(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.

English, Scottish, Welsh, and German: from the Old French personal name Olivier, which was taken to England by the Normans from France. It was popular throughout Europe in the Middle Ages as having been borne by one of Charlemagne's paladins, the faithful friend of Roland, about whose exploits there were many popular romances. The name ostensibly means ‘olive tree’ (see Oliveira), but this is almost certainly the result of folk etymology working on an unidentified Germanic personal name, perhaps a cognate of Alvaro. The surname is also borne by Jews, apparently as an adoption of the non-Jewish surname.