Davros
Psychotic genius and creator of the Daleks, Davros gained favour with a race doomed by centuries of war, the Kaled, and used mutated genetic material to produce a hideous creature, devoid of all emotion apart from evil, promising the Kaled that this was the key to the survival of their race.
Despite doubts and insecurity, the Kaled went along with his plan but were horrified to discover that the mutated creature would need a mechanical encasement in order to survive. The Kaled realized too late that Davros' plan was to create a virtually indestructible, unstoppable race of pure evil, and their civilization was eventually destroyed when the Doctor's compassion prevented him from destroying the Daleks at their inception.