This interesting surname is of Anglo-Saxon origin, and is a locational name from a place thus called, south west of Leicester in Leicestershire. Recorded as "Cossebi" in the Domesday Book of 1086, and as "Cosseby" in the 1236 Feet of Fines for that county, the component elements of the placename are the Olde English personal name "Cossa" (also the first element of Cosham, Hampshire), with the Olde English "by" from the Old Norse "byr", homestead, settlement. Locational surnames were originally given to local landowners, and the Lord of the Manor, and especially to those former inhabitants who left their place of origin to work or settle elsewhere. The surname, with variant spellings Cosbey, Cosbee, Cozby and Cowsby, is well recorded in English Church Registers from the mid 16th Century. On April 13th 1551, Elyzabethe Cosbye and John Berden were married at Christ Church, Greyfriars, Newgate, London. An important Anglo-Irish family of the name have been associated with County Leix since the early fifteen hundreds. Their Coat of Arms is an azure shield with three golden dishes, on a silver canton, a red saltire between four green lucies haurient. A notable bearer of the name was Sir Henry Augustus Montagu Cosby (1743 - 1822), lieutenant-colonel, 1773; knighted, 1786, and lieutenant-general, 1822. The first recorded spelling of the family name is shown to be that of Francis Cosby, (Irish General), which was dated 1548, in the "Records of Queen's County", Ireland, during the reign of Edward V1, known as "The Boy King", 1547 - 1553. 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.