Dooku was a Jedi Master that fell to the dark side of the Force and became the Dark Lord of the Sith Darth Tyranus during the final years of the Galactic Republic. After leaving the Jedi Order, he claimed the title Count of Serenno and, during the Clone Wars, served as Head of State of the Confederacy of Independent Systems. He was the second apprentice of Darth Sidious, the Dark Lord of the Sith whose plan to conquer the galaxy relied on Dooku leading a pan-galactic secessionist movement against the Republic. As such, Dooku immersed himself in the dark side and worked tirelessly to advance his and his master's plans, but ultimately forgot that treachery was the way of the Sith.
You can see Count Dooku in:
- Episode II: Attack of the Clones, 22 BBY (80 years old)
- The Clone Wars (movie), 22 BBY (80 years old)
- The Clone Wars (TV series), 22 BBY (80 years old)
- Episode III: Revenge of the Sith, 19 BBY (83 years old)