Buffy The Vampire Slayer: Ranking The Main Characters From Weakest To Strongest
1. Willow Rosenberg
Willow Rosenberg might have spent the vast majority of the show on a similar level to Xander, Cordelia or Dawn, usually sat behind a computer or with her head buried in a book trying to help her friends conquer some vicious evil away from the battlefield, but by the end of the series there can be no doubt that she's the strongest character of the bunch.
Starting to practise witchcraft in season two, her powers massively improve through seasons three, four and five, until Season 6, when tragedy strikes. With Tara killed in cold blood, Willow harnesses the power of the dark arts to seek her revenge, and with her power she is able to beat Buffy, Giles and Anya (as a vengeance demon) before setting in motion the end of the world.
She would have succeeded, if not for Xander's interference.
In season seven, though no longer evil, she is still easily the most powerful character in the gang, and uses her powers to grant all the Potential Slayers with the strength of a real Slayer. It's a major feat, which changes the very fabric of the world.
Buffy may be the Slayer, able to stop anything that comes against her, but it is Willow who takes the crown.