Ilari is the homeworld of the Ilari, where the ancient tyrant Tieran tried to reclaim power using Kes's body.
Ilari is the home planet of the Ilari, ruled by a hereditary Autarch whose ancestors had overthrown the tyrant Tieran some two hundred years earlier. Tieran had survived by transferring his mind into a series of hosts.
In Warlord, Voyager arrived at Ilari after rescuing Tieran and his followers, and Tieran, now in control of Kes, led troops from a military encampment, murdered the Autarch and declared himself ruler. Janeway worked with the Autarch's son Demmas to stop him, and Tuvok and others infiltrated the palace to free Kes.