This interesting name, with variant spellings Cost(a)in, Costen, Costin etc., has two distinct possible origins, the first and most likely being a derivative of the Medieval male given name Costen or Costin, itself coming from the latin Constantine, (familiarly Costantine), from "constans" meaning steadfast and faithful. The name was popular throughout Europe having been borne by the first Christian ruler of the Roman Empire, Constantine the Great (280-337), and was introduced into England by the Normans. One, Willelmus Filius (son of) Constantini was recorded in the Domesday Book of 1086, and a Herbert Filius Constantini or Costin in the 1207, "Curia Regis Rolls of Norfolk". In the Isle of Man, the surname is a contraction of Mac Austeyn, from Mac Augustin i.e. "son of Augustin", from the Latin "augere", to increase or become. The forms Mac Coisten and Mac Costen were recorded there in 1511. On February 16th 1624, Simon Costan and Bridget Carr were married in Hillingdon, London. One Thomas Costain married Kate Birch at St. Martin-in-the-Fields, London on May 31st 1846. The first recorded spelling of the family name is shown to be that of Hen Costen, which was dated 1182, in the "Pipe Rolls of Leicestershire", during the reign of King Henry 11, known as "The builder of churches", 1154 - 1189. 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.