Recorded as Thorby, Thorlby, Thoresby, Thoresbie, Thursby, Thirby, Thurby, Thurbie, and others, this is an English surname. It is locational either from Thorlby, a village near Skipton in North Yorkshire, or from one of the several places called Thoresby in the counties of Lincolnshire, Nottinghamshire and Yorkshire or possibly even from a lost village which might have been called called Thorby or Thurby although we no proven evidence to support such a theory, except the surviving surname itself. Thorlby is recorded in the famous Domesday Book of 1086 as Torederebi and means "Thor's homestead", a name for the god of thunder in early mythology, and preserved in the weekday name of Thursday. To this was added "by", meaning a farmstead or settlement. Thoresby has the same meaning and essentially is the same name, with the "s" added to aid pronunciation. Locational surnames were given to former inhabitants of a village who moved to another area, and were thereafter best identified by the name of their birthplace. Spelling being at best erratic and local dialects very thick, lead to the development of 'sounds like' spellings. Amongst the recordings of the name are those of Marie Thurbie who married John Holloway at the church of St Gregory by St Pauls Cathedral, London, on December 4th 1632, Robert Thorlby, christened at Witham-on-the-Hill, Lincolnshire, on January 12th 1668, and again in London that of John Thorby christened at St James Clerkenwell on December 11th 1668. Surnames became necessary when governments introduced personal taxation. In England this was sometimes known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.