Ranking The Big Bads From Buffy The Vampire Slayer
1. Angelus
Of all the foes that Buffy has faced, none have managed to connect on an emotional level like her former lover Angel, now Angelus. After brutally murdering a member of a gypsy clan, Angelus was cursed with the restoration of his soul, which effectively turned him into the guilt-ridden remorseful vampire that Buffy fell in love with.
What she didn't know, was that if Angel experienced a moment of pure happiness his soul would be torn from him and he would become a soulless killer once again. Buffy gives him that moment of pure happiness and we are given one of the greatest villains on television.
Angelus is sadistic and cruel and would taunt Buffy (and anyone else he could) with the memories of the man he used to be with her. It's heart-breaking to watch a previously loved character turn so evil in the blink of an eye and seem almost un-saveable, especially after he breaks the neck of Jenny Calendar.
The turn itself was genius storytelling and feels more earned than the brief interlude that was Dark Willow. No other Big Bad succeeds in having an emotional connection close to this other than Willow, but this feels more personal as Angelus' vindictive actions are all directed at Buffy.
Buffy choosing to sacrifice her former love to save the world is appropriately saddening and puts an end to the greatest Big Bad Buffy would ever face.