The Lich King's story in TG (again, presuming it's Warcraft - related). It starts with Arthas' journey. He was a young and promising paladin in Lordaeron. However, the plague in the land and his eagerness to stop it at all costs led him to pick up Frostmourne. This was his downfall. Once he became the Lich King, he resided in Icecrown Citadel. His influence spread far and wide. He had powerful lieutenants like the Dreadlords. His existence was a constant threat to the living races of Azeroth. The heroes of Azeroth had to constantly fight against his forces and eventually, there was a great battle to finally put an end to his reign of terror.
Well, the Lich King in TG (assuming it's related to the general Warcraft context). He has a complex backstory. Arthas, who turned into the Lich King, was driven by his desire to protect his people at first. But the power of Frostmourne twisted him. He then raised armies of the undead, like ghouls, skeletons and abominations. His actions led to many battles and upheavals in the world. For example, his invasion of Quel'thalas was a major event that changed the power dynamics in that region.
The Lich King is a very powerful and iconic character. In many stories related to him in the Warcraft universe, he was once a noble paladin named Arthas. He became corrupted by the cursed blade Frostmourne. As the Lich King, he commands the undead Scourge, causing great destruction and chaos across the land. His story is filled with themes of loss, power, and the struggle between good and evil.