A nobleman from the planet Serreno, Dooku was once a Jedi Master until his faith in the order was shaken following the terrible Battle of Galidraan. Leaving the order and reclaiming his birthright as a nobleman, Dooku would later turn to the dark side and become apprentice to Sith lord Darth Sidious. He used his great wealth and influence to persuade several Republic worlds to splinter from the Republic and form an alliance against the corrupt Galactic Senate. With the founding of the Confederacy, Dooku also reached out to many interplanetary corporate bodies to build vast droid armies to oppose the Republic. With the galaxy at war, Dooku and his master Lord Sidious would use the conflict as a means for the Sith to seize power and dominate the galaxy.
In Attack Of The Clones, Dooku had forged alliances with the Trade Federation and several other corporate and financial bodies. He also interrogated Obi-Wan Kenobi after he was captured inside the CIS droid foundries on Geonosis. Yoda and Mace Windu would later lead the Jedi and the newly-created Republic clone army against Dooku's droid forces, initiating the Battle of Geonosis and starting the Clone Wars. After duelling with Obi-Wan, Anakin Skywalker and even Yoda, Dooku made his retreat, but would resurface again leading the armies of the CIS into battle against the Republic.