The Whispering Tyrant
Tar-Baphon was a powerful wizard-king who ruled central Avistan at the end of the 9th century AR. Killed by the god Aroden himself in 896 AR, he rose as the lich known as the Whispering Tyrant in 3203 AR, and ruled the country of Ustalav for centuries. He was finally defeated by the Shining Crusade in 3827 AR and imprisoned within his capital of Gallowspire.
He was inadvertently set free when the rifts opened up, and has been busy raising an undead army.
Read more here: