5. Cordelia Chase
After Doyle’s death, Cordelia was granted his psychic visions by the Powers That Be. Later, she became part-demon and developed light-based healing powers. Eventually, Cordy became a Higher Being, essentially an omniscient angel, where her abilities included perceiving the whole of history (she could see Angel’s past as Angelus).
The most powerful foe that Buffy ever faced was Glorificus, the hell goddess. She was far stronger than Buffy, possessed super-speed and was near-invulnerable (only a Troll’s hammer could harm her). She could also recharge her strength by absorbing a person’s mental energies by touch.
3. Willow Rosenberg
Willow might not be an actual goddess, but she is perhaps the most powerful witch who has ever lived – she was certainly the only person with enough magical ability to activate every Potential Slayer. The comics have also revealed that Willow is possibly immortal and will live until at least two hundred years into the future.
The being known as Jasmine was a rogue member of the Powers That Be – the supreme beings of the universe. When on Earth, she was able to “enslave” the entirety of humanity just with the power of her image alone. Similar to Glory, Jasmine needed to consume people’s energies to stay strong – but she did it by absorbing a person whole.
Once an all-powerful Old One – purebred demons from the dawn of time – Illyria later possessed Fred Burkle’s form. She literally had the powers of a god – including indestructibility, time manipulation, shapeshifting (at least into Fred’s form) and inter-dimensional teleportation. Oh, and she could also talk to plants.