Quintessa

Quintessa is a Cybertronian sorceress and one of The Creators of the Cybertronian race. She is the main antagonist of Transformers: The Last Knight and a possible antagonist in the sequel, Transformers 6.

History
After Optimus Prime crash-landed on Cybertron, Quintessa corrupted him and sent him to destroy Earth, as the planet was really the dormant body of Unicron.

Eventually though, Optimus breaks free from Quintessa's control and turns on her. However, Quintessa teams up with Megatron to activate an ancient machine to destroy the Earth. The Autobots soon intervene, and Quintessa is seemingly destroyed by Bumblebee while Viviane deactivates the machine by removing the staff from it.

However, Quintessa somehow manages to survive. Disguised as a human, Quintessa meets with a group of scientists studying Unicron and offers them a way to destroy the being.