John William was born about 1690, in Penderyn, Breconshire, Wales as the son of John and Joan. He had at least 2 sons and 4 daughters.
English (of Norman origin): from the Middle English personal name William, Willam, Willem, an Old Picard and Norman French form of ancient Germanic Willihelm, composed of the elements wil- ‘will, desire’ + helm- ‘helmet, protection’. This Norman personal name became widely used in England, Scotland and Wales after the Conquest, mainly no doubt in honor of the Conqueror himself. By the 13th century it had already become the most popular personal name in England. A Parisian form of the name Guillaume was also sometimes used (see Gillam ), which in medieval Wales was adopted as Gwilym (see Gwilliam ).
Americanized form (translation into English) of French Guillaume .