A reeve was responsible for the management of the laws and finances of an area. The position evolved in time from the original Anglo-Saxon role as a steward or governor into one more of a local head of the judiciary or a bailiff. The word was usually linked to the area it managed e.g. portreeve, shire-reeve. Shire-reeve eventually became sheriff.
Reeves in the SCA
Some groups call their Exchequer by this name.