Imperial Count (German: Reichsgraf) was a title in the Holy Roman Empire. In the medieval era, it was used exclusively to designate the holder of an imperial county, that is, a fief held directly (immediately) from the emperor, rather than from a prince who was a vassal of the emperor or of another sovereign, such as a duke or prince-elector. These imperial counts sat on one of the four "benches" of Counts, whereat each exercised a fractional vote in the Imperial Diet until 1806.
In the post-Middle Ages era, anyone granted the title of Count by the emperor in his specific capacity as ruler of the Holy Roman Empire (rather than, e.g. as ruler of Austria, Bohemia, Hungary, the Spanish Netherlands, etc.) became, ipso facto, an "Imperial Count" (Reichsgraf), whether he reigned over an immediate county or not.
In the Merovingian and Franconian Empire, a Graf ("Count") was an official who exercised the royal prerogatives in an administrative district (Gau or "county"). A lord designated to represent the king or emperor in a county requiring higher authority than delegated to the typical count acquired a title which indicated that distinction: a border land was held by a margrave, a fortress by a burgrave, an imperial palace or royal estate by a count palatine, a large territory by a landgrave. Originally the counts were ministeriales, appointed administrators, but under the Ottonian emperors, they came to constitute a class, whose land management on behalf of the ruling princes favoured their evolution to a status above not only peasants and burghers, but above landless knights and the landed gentry. Their roles within the feudal system tended to become hereditary and were gradually integrated with those of the ruling nobility by the close of the medieval era.