Thoueris

Thoueris was an Osirian who posed as a goddess.

Rise to power
Thoueris came to Earth and hid in the River Nile. She demanded the Egyptians pay her tribute. She used a ring on her hand to control crocodiles in the river, using them to kill those who opposed her.

Downfall
The Eighth Doctor antagonised her and she attempted to climb the cliff the Doctor was on. The Doctor blinded her temporarily with oil, then lit the oil. This made Thoueris fall, but not before the Doctor took her ring. He used the ring to make the crocodiles attack and kill her. (DWM: The Power of Thoueris!)