History: Glorificus, a.k.a That Which Cannot Be Named, went by a couple of names in her time on Earth. There was Ben, a hospital worker and a real bore; and there was Glory, a gorgeous woman with killer everything. Although neither of those earthly identities was really adequate for this goddess, she managed to have some fun as the latter. The whole setup was a desperate attempt by the Order Of The Dragon to keep Glorificus from finding the Key (a.k.a Dawn), which would have let her break down barriers between dimensions, resulting in hell on Earth.
Glory began taking over Ben’s body more frequently and searching for the Key among Sunnydale’s residents with the help of her minions. She knew to look for a pure being that would inspire the slayer’s protection, which is why she ditched Spike and went after Tara. Their encounter cost Tara her sanity (temporarily) and incited Willow and Buffy’s wrath. But this was no mere vamp up against a vampire slayer and witch; Glory handily beat them in their melee.
How’d they bite it?: No one thought taking down a god would be easy, but they couldn’t have imagined it would come at such a high cost either. In “The Gift,” the Scoobies marshaled their forces: Willow had her magic; Buffy, Olaf’s Hammer; and Xander brought a wrecking ball to a supernatural-forces fight. While Spike, Anya, and Giles battled Glory’s minions, the rest of the Scoobies did a number on Glory. Buffy beat her senseless with the troll hammer, which brought back Ben. But Giles knew they couldn’t risk Glory taking control of his body again, so he smothered him, extinguishing Glorificus once and for all.
It wasn’t a wrap, though: Dawn’s blood had been spilled, completing the ritual that allowed demons to make their way into our dimension. She offered to sacrifice herself, but after recalling the first slayer’s words from “Intervention,” Buffy realized her own blood could also close the portal. So she sacrificed herself to save the world for the umpteenth time. That wasn’t quite her epitaph, but you get the point.