First found in Yorkshire where they were anciently seated as Lords of the Manor. After the Battle of Hastings in 1066, William, Duke of Normandy, having prevailed over King Harold, granted most of Britain to his many victorious Barons. It was not uncommon to find a Baron, or a Bishop, with 60 or more Lordships scattered throughout the country. These he gave to his sons, nephews and other junior lines of his family and they became known as under-tenants. They adopted the Norman system of surnames which identified the under-tenant with his holdings so as to distinguish him from the senior stem of the family. After many rebellious wars between his Barons, Duke William, commissioned a census of all England to determine in 1086, settling once and for all, who held which land. He called the census the Domesday Book, indicating that those holders registered would hold the land until the end of time. Hence, conjecturally, the surname is descended from the tenant of the medieval village of Northorpe which washed out to sea in earlt times. It was recorded in the Domesday Book census of 1086 when Walter held the village from Drogo de Beuvierre a Nomran Baron. The family is conjecturally descended from Walter of Northorpe.

Some of the first settlers of this family name or some of its variants were: Joshua Northrop, who settled in Nova Scotia sometime between 1598 and 1867; Joseph Northup, who came to Nova Scotia sometime between 1598 and 1867; Cobb Northrup, who arrived in Nova Scotia sometime between 1598 and 1867.

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