This name is of English locational origin from a place called Killingworth in Northumberland. The name means "The word of Cylla's people". Another spot thus called may also have existed in Norfolk as the early recordings of the name all come from this county. In 1388 one Thomas de Killingworth was vicar of Windham, Co. Norfolk. A Richard Killingworth is recorded there in 1561. Grantham Killingworth (1699-1778) was a baptist controversialist and pamphlet publisher. The earliest spelling of the place name Killingwrth appears in the Book of Fees dated 1242. The first recorded spelling of the family name is shown to be that of Adam de Kellyngworthe which was dated 1273, in the "Hundred Rolls of Norfolk". during the reign of King Edward 1, known as "The Hammer of the Scots" 1272 - 1307 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.