Count Dooku is a Star Wars character first introduced in Star Wars Episode 2: Attack of the Clones. He also briefly appears in Star Wars Episode 3: Revenge of the Sith. He is portrayed by Christopher Lee. Count Dooku appeared in several video games, all related to the Star Wars prequel trilogy.
Count Dooku used to be a Jedi before becoming a Sith Lord and forming the Seperatist movement. He has a very prominent role in Star Wars Episode 2. He secretly prepares the Clone Wars and the eventual downfall of the Jedi for Emperor Palpatine. After starting the Clone Wars, he fights Anakin and Obi-Wan, defeating both of them before fighting Yoda and fleeing.
Count Dooku was also a prominent figure in the critically acclaimed animated series Star Wars: Clone Wars. He also makes appearances in the animated movie Star Wars: The Clone Wars and the animated TV show Star Wars: The Clone Wars. It's revealed in these shows that he's the commander of the Separatist forces and that the only way to end the Clone Wars is by stopping Dooku.
Count Dooku makes a brief appearance at the beginning of Episode 3 where he duels Anakin and Obi-Wan over Coruscant and is executed by Anakin.
In Video Games
Count Dooku appeared in all Star Wars video games that were set during Episodes 2 or 3 and during the Clone Wars. This means that Dooku has appeared in most recent Star Wars games. He appeared in the Star Wars Battlefront games as a "general" that could be played at certain times during matches. In these situations, Dooku could swing his lightsaber as well as use lightning to dispose of his foes.
Dooku has appeared in all the Lego Star Wars games as both a boss as well as a playable character. In the Wii version of Star Wars: The Force Unleashed, Dooku could be played in the lightsaber duel mode. Dooku was also present in all the tie ins for the movies in which he was featured (Star Wars: Episode III - Revenge of the Sith, Star Wars: Episode II - Attack of the Clones).
Dooku's actions are the same in the games as they are in the movies. Usually, Dooku is featured as boss.