Recorded in an extraordinary number of spellings including Castleton, Castledone, Castledene, Castledine, Casseldine, Castletine and many others, this is an English surname. It is locational and almost always originates from the town of Castleton, in the county of Derbyshire. There are other villages called by the same name in both Lancashire and Yorkshire, but in general it is the Derbyshire 'Castleton' which has provided the surname. The surname is equally popular in certain parts of Derbyshire as both Castleton and the dialectal Castledine, whilst in other areas from the middle of the 16th century the spelling forms include Caselden, Casseldine, Castletine, and Casteldon. The town is first recorded in the famous Domesday Book of the year 1086 as 'Castellum Willelmi peuerel', or 'the castle of young William'. He was the youngest (natural) son of William, The Conqueror, and was granted lands in various parts of England. By the 13th century the place is recorded in the charters of Derbyshire as 'Castelton', or 'the place (tun) by the castle'. Early examples of the surname recordings taken from the church registers include Alice Castleton, christened at the church of St Benet Fink, on February 23rd 1564, Bendicta Caselden, christened at St Mary Abchurch, on June 27th 1621 and William Casseldine, a witness at the church of St. Mary's Whitechapel, on February 18th 1750. All recordings shown are from the registers of the city of London, on February 18th 1750. The first recorded spelling of the family name is shown to be that of Sir Richard de Castillton, which was dated 1298, in the English roll of the 'battell of Falkirk'.