Council of Gondor
From Tolkien Gateway
The Council of Gondor took authority over Gondor after the loss of Ondoher left it kingless, and it acted under the control of Steward Pelendur. The Council is known from Arvedui's claim on Gondor's throne.
History
It was traditional among the Men of Númenor for the King to maintain a Council of the Sceptre composed of nobles from each of the main regions of Númenor, together with the King's Heir as advisers.
Obviously that their descendants in Gondor followed a similar system 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.