Simplify the following text for a Grade 6 native English-speaking person.
Original: Dooku is the main antagonist of Star Wars Episode II : Attack of the Clones and throughout the fictional events of the Clone Wars and is a supporting villain in Star Wars Episode III : Revenge of the Sith . Count Dooku plays a substantial role in the `` Expanded Universe '' of novels , comic books , and video games .
Simplified: Dooku is one of the major characters in Episode II : Attack of the Clones .