Final answer:
King Leopold II of Belgium owned the Congo Free State and the main raw material extracted was rubber.
Step-by-step explanation:
The tyrannical ruler who 'owned' the Congo Free State was King Leopold II of Belgium. He established the International African Association with the goal of 'civilizing' the natives of Africa, but in reality, he exploited the region's resources for his personal wealth. The main raw material extracted from the Congo Free State was rubber.