Yhwach

Yhwach is the main antagonist of the final major arc in Bleach (the Thousand-Year Blood War arc).

He is the founder and leader of the Quincy empire known as the Wandenreich, and he is revealed to be the original ancestor of all Quincies — often referred to as the "Father of the Quincy." His most defining trait is his ability "The Almighty", which allows him to see all possible futures, choose which ones he wants to make reality, and even rewrite events that have already happened to him.

Personality-wise, Yhwach is extremely calm, regal, arrogant, and utterly ruthless. He views almost everyone (even his own subordinates) as tools or extensions of his own power, and he speaks in a very measured, almost philosophical manner. He has a deep obsession with ending the cycle of life and death created by the Soul King.

Physically, he is usually depicted as a tall, imposing man with long black hair, a mustache and beard, striking red eyes, and distinctive black-and-gold Quincy attire (later evolving into even more regal robes).

In short: ancient, god-like Quincy king with near-omniscient future-sight powers, cold and calculating, and the most powerful enemy Ichigo and the Soul Society ever face.