English: habitational name from any of numerous places named with Old English halig ‘holy’ + well(a) ‘well’, ‘spring’, such as Holwell in Dorset and Oxfordshire. (Reaney suggests it could also have been a topographic name with the same etymological origin.) However, the present-day concentration of the name in Northamptonshire would suggest that Holwell in Leicestershire, which has a different etymology, from Old English hol ‘hollow’ + wella, was most likely the primary source of this form of the surname. There is also a Holwell in Hertfordshire of the same derivation, as well as places called Halwill and Halwell in Devon, Holywell in Cambridgeshire, Cornwall, Clwyd, and Northumberland, and Halliwell near Manchester, all of which could have contributed to the surname.
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4