Arab Union
Such arrangements are not to be confused with supranational entities which are not states and are not defined by a common monarchy but may (or not) have a symbolic, essentially protocollary, titled highest office, e.g., Head of the Commonwealth (held by the British crown, but not legally reserved for it) or 'Head of the Arab Union' (14 February - 14 July 1958, held by the Hashemite King of Iraq, during its short-lived Federation with Jordan, its Hashemite sister-realm).