Originally in Anglo-Saxon England the reeve was a senior official with local responsibilities under the Crown e.g. as the chief magistrate of a town or district. Subsequently, after the Norman conquest, it was an office held by a man of lower rank, appointed as manager of a manor and overseer of the peasants. In this later role, historian H. R. Loyn observes, "he is the earliest English specialist in estate management."
Anglo-Saxon England 
Before the Conquest, a reeve (Old English gerefa; similar the titles greve/gräfe in Low Saxon languages of Northern Germany) was an administrative officer who generally ranked lower than the ealdorman or earl. The Old English word gerefa was originally a general term, but soon acquired a more technical meaning. Different types of reeves attested before the Conquest include the high-reeve, town-reeve, port-reeve, shire-reeve (predecessor to the sheriff), reeve of the hundred and the reeve in charge of a manor. The word is often rendered in Latin by the historian Bede as prefectus and some early Anglo-Saxon charters, while West-Saxon charters prefer to reserve the term prefectus for ealdormen.
England in the early 11th century employed the services of shire reeves to assist in the detection and prevention of crimes. Groups of 10 families or "tithings" were commissioned for an early form of "neighborhood watch", and were organized into groups of 100 families or "hundreds." The hundreds were supervised by a constable. Groups of hundreds within a specific geographic area were combined to form shires and were under control of the king. The reeve of an entire shire was a Shire-reeve, predecessor to the Sheriff.
After the Conquest 
After the Norman conquest a reeve became the word used for the man appointed to supervise the work done on the land comprised in a manor. He has been described as "the pivot man of the manorial system". He had to oversee the work which the peasants were bound to perform, as an obligation attached to their holding of land in the Manor, for the lord of the manor on the demesne land and act generally as the overseer of the serfs and peasants on the estate. He was also responsible for many aspects of the finances of the manor such as the sale of produce, collection of monies and payment of accounts. He was usually himself a peasant and was subject to the steward, but the steward might not always be resident on the manor and would not usually concern himself with day to day working. The reeve was chosen once a year, generally at Michaelmas, but a good man who carried out his duties efficiently and was trusted by the lord and the peasants was likely to stay in office more or less permanently. By the 14th century the reeve was often a permanent officer of the manor.
In some manors the reeve was appointed by the lord of the manor, but in others he was elected by the peasants, subject or not to a right of veto by the lord. It depended on the custom of the manor, but there was an increasing tendency for election to be favoured. No doubt an elected reeve was more willingly obeyed and sometimes the peasants generally would be made financially liable if an elected reeve defaulted.
Depiction by Chaucer 
There is an exceptional literary portrait of a reeve in the second half of the 14th century. The reeve is one of the pilgrims making their way to Canterbury in Chaucer's Canterbury Tales and the Prologue paints a vivid picture of this man, who had originally been a carpenter but had served as reeve of a manor for many years and had grown old in service. Chaucer describes a highly efficient servant, impossible for any man to deceive or outwit, never in debt and knowing exactly how much the manor should produce. It is an early picture of a completely reliable accountant, rather a cold individual but indispensable.
See also 
- Loyn, Anglo-Saxon England and the Norman Conquest, 2nd ed. 1991:356.
- see H.S.Bennett: Life on the English Manor (Cambridge 1937) pp.166ff
- Canterbury Tales. Prologue lines 590 ff. When he comes to tell his tale, the Reeve's Tale is appropriately about a miller who stole corn from two students who then get their revenge in bed with his wife and daughter.