who defeated obi-wan kenobi in a lightsaber duel
Obi-Wan Kenobi In the spaceport city Mos Eisley, Obi-Wan uses the Force to trick Imperial troops into letting them through a military checkpoint. They enter a local cantina and make a deal with two smugglers, Han Solo and Chewbacca, to fly them to Alderaan aboard their ship, the Millennium Falcon. During the journey, Obi-Wan begins instructing Luke in lightsaber combat. He suddenly becomes weak and tells Luke of "a great disturbance in the Force". Emerging from hyperspace, the party finds that Alderaan has been destroyed by the Empire, and the Falcon is attacked by an Imperial TIE Fighter. The trio chase the TIE fighter to the Death Star, and subsequently get caught in the space station's tractor beam. On board the Death Star, Obi-Wan shuts down the tractor beam, but Darth Vader confronts him and they engage in a lightsaber duel. Obi-Wan uses the duel to distract Vader as Luke, Leia, Han and Chewbacca escape to the Falcon. Although Vader strikes Obi-Wan down, his body mysteriously vanishes the moment he dies. At the climax of the film during the Rebel attack on the Death Star, Obi-Wan speaks to Luke through the Force to help him destroy the Imperial station.
Count Dooku In the opening of Star Wars: Episode III – Revenge of the Sith, set three years later, Dooku and Separatist commander General Grievous kidnap Supreme Chancellor Palpatine—Sidious' alter ego—as part of a plan orchestrated by Palpatine to lure Anakin to the dark side of the Force. Anakin and Obi-Wan board Grievous' ship and confront Dooku, who knocks Obi-Wan unconscious, leaving Anakin to face the Sith Lord alone. Anakin gives in to his hatred of Dooku and uses the dark side to overpower him, severing both of Dooku's hands and leaving him helpless. Palpatine then tells Anakin to execute Dooku on the spot; after initial hesitation, Anakin brutally decapitates Dooku. This act sets off a chain of events that leads to Anakin's eventual fall to the dark side and transformation into Darth Vader.