Count Dooku is a fictional character from the Star Wars universe, appearing as the main antagonist of Star Wars Episode II: Attack of the Clones and as a supporting villain in Star Wars Episode III: Revenge of the Sith, portrayed by Christopher Lee. Dooku is the primary antagonist in the events of the Clone Wars. He also plays a substantial role in the "Expanded Universe" of novels, comic books, and video games. Besides the Star Wars prequel films, Christopher Lee also voiced Dooku in Star Wars: The Clone Wars. In his television and video game appearances, Dooku is portrayed by voice actor Corey Burton.

Although he was once a respected Jedi Master, Dooku became disillusioned with the Jedi Council and became one of the "Lost Twenty" to leave the Order. A few years before the events of Episode II, Dooku falls to the dark side of the Force, at which time he is initiated into the ways of the Sith by Darth Sidious, who bestows upon his new pupil the title of Darth Tyranus.

Tyranus leads the Separatists in the Clone Wars, which in turn lead to the destruction of many worlds throughout the galaxy. During the Clone Wars he trains General Grievous, leader of the Droid Armies, and Asajj Ventress, his personal assassin. In Revenge of the Sith, Dooku is killed by Anakin Skywalker, who eventually replaces him as Darth Sidious' third apprentice, Darth Vader.