Gerontocracy
A gerontocracy is a type of oligarchical rule in which an organization is governed by a small group of elderly leaders who wield the greatest influence. Those exerting the most power may not occupy formal leadership roles, but rather dominate those who do: during the era of the Twelve Immortals of Lúinwë, it was facetiously remarked that "the 180-year-olds are summoning meetings of 170-year-olds to decide which 160-year-olds should retire".
Gerontocracy's strength lies in its stability, which can be more suitable for institutions that impart principles that remain constant over time. However, in institutions required to adapt to swift transformations, the diminished faculties of the aged may potentially hinder effective leadership.
The city-state Lúinwë is governed by a gerontocracy system.
Pedocracy
A pedocracy is a government led by the learned, savants, and scholars. Ithengee, Hinnbjalf, and Vynnendar exemplify pedocracies.