Tyranith's body in the Cathedral
Tyranith is a mysterious hero who attempted to put an end to Eidolon's reign at some point in time before the events of Hexen II, possibly shortly after the invasion.
He explored the occupied territories of Thyrion and solved many of its intricate puzzles. He left behind several notes to potential future adventurers, giving them some basic information about the present situation and the challenges that lie ahead of them.
Tyranith came very close to his ultimate goal, Eidolon, yet he was eventually overwhelmed by his minions and perished somewhere within the Cathedral. His body is eventually found by the heroes who followed in his footsteps. They continue his quest and ultimately defeat Eidolon.