Deposed Ilari autarch who survived for centuries by moving his mind into new hosts, and who seized Kes's body in a bid to retake power.
Tieran had ruled the Ilari until he was overthrown by the ancestors of the current Autarch two centuries earlier. He survived by transferring his mind into one host body after another. In Warlord, his dying host was beamed aboard Voyager, and he moved his consciousness into Kes.
Controlling Kes, Tieran returned to Ilari, killed the Autarch and declared himself ruler. Through a mind-meld with Tuvok, Kes fought back from within, and the crew isolated and destroyed Tieran's neural pattern, allowing the rightful heir Demmas to take the throne.