Peer of the Realm

Peer of the Realm is a term for a member of the highest social order (not considering the ruling dynasty) in a kingdom, notably:

a member of the Peerage (noble and equivalent titles granted by the British crown; actually there are several peerage systems, such as the peerages of England, of Scotland, of the UK)
the English rendering a member of a similar order in another realm, especially the French title pair as used in the French kingdom and the crusader state kingdom of Jerusalem