Council of Gondor
In his account of Arvedui's claim on Gondor's throne, Tolkien once mentions a body known as the Council of Gondor, that took authority over Gondor after the loss of Ondoher left it kingless. Except for the fact that it acted under the control of Steward Pelendur, we are told almost nothing of this Council or its normal function.
It was traditional among the Men of Númenor for the King to maintain a council of advisers, and it is not unreasonable to presume that their descendants in Gondor followed a similar system. The Númenórean 'Council of the Sceptre' was composed of nobles from each of the main regions of Númenor, together with the King's Heir. It is fair to assume, then, that Gondor's Council was made up from representatives of each of the South-kingdom's separate lands, probably in addition to the King's heir, and apparently the Steward as well.