Just finished a re-read and honestly, the main antagonist shifts throughout. Early on, it's the arrogant Young Master of the Sky Sword Sect, Chu Tianxiao, who bullies the weak. But he's more of a starter villain. The real pressure comes from the massive, ancient 'Demon Sect' lurking in the shadows, pulling strings across the continent. Their leader, the enigmatic Netherworld Demon Sovereign, is built up as this terrifying endgame force, but we barely see him directly. For me, the most compelling opposition is actually the protagonist's own former sect elder, Bai Wuchen. That betrayal from someone who was supposed to guide him cuts deeper than any demonic army. The book keeps you guessing about who the true final enemy is.
Sometimes it feels like the cultivation world itself, with its cruel rules and constant power struggles, is the ultimate antagonist. The hero's journey is as much about overcoming that system as it is about defeating any single person.