Main villain of Samurai Jack
Aku is part of a primordial mass broken by Odin, Ra and Vishnu. The broken part crashed on Earth and killed the dinosaurs. It stayed until Feudal Japan. The Emperor tried to eliminate it with a poison arrow. It made the mass known as Aku and became more human. He trapped the Emperor to ravage Japan. When the Emperor came back, he used his sword which is made to hurt Aku. Aku split into many and pick the remains of Samurais and attacked the Emperor. The Emperor banished the evil abombination. Aku warned the Emperor that he will return. Aku got banished in the form of a tree until less than a decade by an eclipse. Aku ruined Japan for many years. When the Emperor's son came back, Aku sent the son to the future. Aku wanted a robot army. He hired a group of scientists to make robots. The result is the X-Models. Most of the X-Models were destroyed. The scientists created the Beetle Drones.