Recorded in various spellings including Milnthorpe, Millthorpe, Milnethorp, Milthorp, and Milnethorpe, this is an English surname. It is medieval and locational, originating from either the village of Milnethorp, near Wakefield, in the West Riding of Yorkshire, or possibly in a very few cases, from Milnethorp, a parish in the former county of Westmorland, in the far north of the country, or Millthorpe, a village in Lincolnshire, called Milnetorp in the rolls of the year 1202. However nearly all the early recordings relate to the Yorkshire village. In all case the place name and hence the later surname means the "mill at the outlying settlement" from the pre 7th century Norse-Viking word "torp" and the Olde English word "myllen", usually describing a water mill, as windmills were rare before the 15th century. The early surname recordings taken from surviving registers of the medieval period include: Geoffrey de Milnethorp of Lincolnshire in the Hundred Rolls of the year 1273, and Robertus de Milnethorp and Joanna Milnthorp, both in the Poll Tax rolls of Yorkshire in the year 1379.