For a short while I was hesitating between Yulmu (Tale of Nokdu) and Homelander (The Boys), but after a careful weighting pros and cons, I'm opting for Yulmu.
The reasons for choosing Yulmu are several. First, he's just a human. He was born a human and raised as one. He was surrounded by good people, happy people and yet their happiness and brightness did not penetrate his soul. Whatever happened after his big reveal (and what led to it) was of his own making. And he did that with a conscience not clouded by any regret. He ordered to kill Prince Yeongchang, a child, just because he wanted to show who is reaching for power. He ordered to wipe out the whole Widow's Village, to slaughter every woman there and to kill Muwoldan (something that Nokdu threw in his face with disdain). He was ready to force his will on Dongju, to blackmail her into subjugation just because he thought he owned her. And what is more, he finally achieved his goal - a rare feat for villains in the shows/movies. Here the good guys failed and did not stop him from staging a coup and overthrowing Gwanghaegun.
Homelander is immoral, brake-free Yulmu on steroids. This is why, even though he is the epitome of the most villainous villain, he has to give up the first place. He was born as the experiment, he was raised in the lab like an animal, he was never shown any form of human emotion - he had absolutely no source to take from. He killed the one person that was relatively closest to him just as a show of the force, unhinging him even more. He had no apparatus to feel, yet deceived the public to be the benevolent superhero. Because everyone who knows him - fears him. Even the US Army.
