Count Dooku
Count Dooku of Serenno, also known by his Sith name Darth Tyranus, was a prominent political figure and former Jedi Master who fell to the dark side of the Force and became Darth Sidious' second Sith apprentice. He played a pivotal role in Sidious' rise to power, leading the Confederacy of Independent Systems, made up of numerous planetary systems seeking independence from the Republic, throughout the Clone Wars, and engineering the creation of the Republic's clone army. Although Dooku hoped this would allow him to rule the galaxy alongside Sidious, whom he secretly plotted to overthrow, he was ultimately betrayed by his master, who arranged his death at the hands of his eventual replacement, Anakin Skywalker.