Recorded as Gilbert and the patronymic Gilbertson, this is an English surname, but one recorded throughout the British Isles. It is of Norman-French and even earlier pre 7th century Germanic origins. It derives from the personal name variously spelt as Gislebert, Guilbert or Gilebert. However spelt it is a compound with the elements "gisil", meaning a noble youth, and "berht", bright or famous. It is first recorded in England in the famous Domesday Book of 1086 and in the Latinized form of Gislebertus, and appears as a surname in the early 13th century (see below). The given name as Gilbert was very popular in medieval England, partly owing to the fame of St. Gilbert of Sempringham, (1086 - 1189), and the founder of the only native English monastic order. Early examples of the surname recording taken from surviving church registers of the diocese of Greater London include Anna Gylberte, who was christened on June 20th 1548, at St. Michael's Cornhill, and Anne, the daughter of Harry Gilbert, who was christened on December 21st 1558, at St. Matthew's, Friday Street, also in the city of London. Henry Gilbert, aged 38, was a "famine" emigrant who sailed from London aboard the ship "Northumberland", bound for New York on April 9th 1846. The first recorded spelling of the family name is shown to be that of Willelmus Gilberti. This was dated 1202, in the Curia Regis rolls of the county of Wiltshire, during the reign of King John of England, 1199 - 1216. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.
[Read more: http://www.surnamedb.com/Surname/Gilbert]
Gilbert Genealogy Y-DNA Project: [http://www.janegilbert.org/gilbertdna/]