R. or r. may refer to: * ''

Reign A reign is the period of a person's or dynasty's occupation of the office of monarch of a nation (e.g., Saudi Arabia, Belgium, Andorra), of a people (e.g., the Franks, the Zulus) or of a spiritual community (e.g., Catholicism, Tibetan Budd ...

'', the period of time during which an Emperor, king, queen, etc., is ruler. * ''Rex (title), Rex'', abbreviated as R., the Latin word meaning King * ''Regina'', abbreviated as R., the Latin word meaning Queen regnant, Queen * or , abbreviated as r., used in historiography to designate the ruling period of a person in dynastic power, to distinguish from his or her lifespan (e.g. "Charles V (r. 1519–1556)") * Abbreviation R., meaning ''"the Crown"'' or ''"State (polity), the state"'' in criminal prosecution in Commonwealth realms (e.g. ''"R. v Defendant"'') * R. (R. Kelly album), R., an album by American singer R. Kelly

See also