The name William is derived from the Norman form of an Old French personal name composed of the Germanic elements wil, will and helm, helmet (i.e., Wilhelm). The personal name William was introduced into England at the time of the Conquest of 1066, and within a very short time it became the most popular given name in England, mainly no doubt in honor of the "Conqueror" himself.

The surname William was first recorded in the 1279, "Hundred Rolls of Oxfordshire," with one Richard William. The  patronymic* version Williamson, was first recorded in the mid 14th Century by an ancient Scottish tribe called the Straclyde Britons.   An interesting name bearer was Alexander Williamson (1829 - 1890), a missionary, who was ordained at Glasgow in 1855, and worked under the London Missionary Society in China from 1855 - 1858; he was an agent in China to the National Bible Society of Scotland from 1863 - 1890.

A Coat of Arms granted to a Williamson family in Lancaster is a gold shield, a chevron engrailed between three trefoils slipped black, the Crest being a demi eagle displayed gold, holding in the beak a trefoil slipped black. The motto "Murus aeneus conscientia sana", translates as "A sound conscience is a wall of brass".

The first recorded spelling of the family name is shown to be that of Arnald Williamssone, which was dated 1360, in the "Court Rolls of the Borough of Colchester", during the reign of King Edward III, known as "The Father of the Navy", 1327 - 1377.

Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax.

Throughout the centuries, surnames in every country have continued to develop often leading to astonishing variants of the original spelling.

Rankings for Williamson:
Scotland has 70 out of every 100
England and Wales has 169 out of every 500
United States has 213 out of every 88,799

* Most cultures also started to use the father's name to separate two individuals to avoid confusion about who a person with a certain given name really was. A second name was added that derived from that of the person's father or paternal ancestor, usually by the addition of a suffix meaning "son" or "daughter".