10 Video Game Bosses Who JUST WOULDN'T DIE

Even though Sin is Final Fantasy X's primary antagonist, religious leader Seymour Guado is a bigger thorn in our heroes' side. The horn-haired mage claims to be an ally to Tidus and his companions at first, but later proves to be a big fan of world domination.

After defeating Seymour, Tidus has no reason to believe the crazed sorcerer will return. Soon after, it's revealed the land was forever filled with wandering spirits called Unsents, who have yet to move onto the afterlife. Since Seymour is an Unsent, he has no desire to leave the world until he has tended to unfinished business.

Although Seymour only appears four times, players will quickly learn to hate the character, due to his brutally unfair tactics. His third incarnation, Seymour Flux, is infamously difficult, since he can neutralise the heroes' summons after one use. Flux often performs two devastating attacks in a row, giving Tidus' teammates no opportunity to counter or heal. For this reason, players have zero chance against Flux unless they grind like crazy and go into the bout with a bulletproof strategy.

Even then, you still have another fight before Mr. Guado is down for good.

He may not be the arch-villain, but Seymour's refusal to die makes him one of the most infuriating enemies in the entire franchise.