Buffy's close friend who transitions from a shy student to a powerful witch. She forms a romantic relationship with fellow witch Tara Maclay and later studies under Giles. In Season Six, grief over Tara's death triggers a dangerous addiction to dark magic, leading to violence and near-apocalyptic behavior. Eventually redeemed through her friends' support, she plays a pivotal role in the final battle by magically empowering all Potential Slayers to defeat the First Evil.