Vicarius

Vicarius is a Latin word, meaning substitute or deputy.In ancient Rome, this was the title of varies officials, each specifically assigned to second an individual superior, after whom his full title was generally completed.

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Roman Republic
Roman Empire
PrincipateDominate
Western EmpireEastern Empire
Ordinary Magistrates:
Extraordinary Magistates:
Mandatory officials / Miscellaneous Offices:
Politics and Law:

Under the Dominate, a vicarius was the imperial 'vicar' (deputy) in charge of a group of Roman provinces called diocese. The post was introduced under Diocletian who reformed the Roman Empire, collegially, as Tetrarchy. Under this system, the empire was ruled by two Augusti, each assisted by a deputy and successor styled Caesar (these deputies were soon abolished as a regular feature - only two emperors were left). The eastern and western empires remained each divided in two large praetorian prefectures.

Each of the four prefectures, which were not abolished, was run by a Praetorian Prefect (originally the 'chief of staff' of each of the four imperial tetrarchs) and contained several dioceses and the vicarius of each diocese was responsible for a number of provinces, each with its own governor.

The various prefectures, dioceses and provinces are listed systematically in hierarchical groupings in the article Roman province

See also: Vicarius, Aedile, Augusti, Augustus, Byzantine Empire, Caesar, Caesar (title), Censor, Collegiality