This is an English habitation surname. It originates from the village of Cockayne Hatley in Bedfordshire, recorded as Hattenleia, in the Anglo-Saxon Chronicle of 960 AD or from East Hatley and Hatley St. George, recorded as Hateleia in the Cambridge Inquisitions of 1080. The three villages are close together on a piece of raised land, the first part of the name is said to have derive from "hatt", meaning the top of the hill, with "leah", a fenced area suitable for farming.
The first recorded spelling of the name in parish registers is thought to be that of one John Hatley. He married Agnes Barlow at Grantchester, in Cambridgeshire, 23rd Jan 1541. Other early mentions of the name are Arnold de Hateleia 1198 Bedfordshire Fleet of Fines and Agnes de Hatleye 1275 Subsidy Rolls Worchestershire.
On the whole the name is spelt Hatley, but I have found the following variations, Attlee, Hadleigh or Hadley, Hateley.