General Grievous

Grievous was a Kaleesh cyborg general who held the titles of Supreme Commander of the Droid Army and warlord for the Confederacy of Independent Systems during the Clone Wars. Originally a warrior from the planet Kalee, Grievous chose to receive cybernetic implants to increase his combat prowess. He was recruited by Count Dooku to lead the Separatist Droid Army of the Confederacy of Independent Systems, and trained in the art of lightsaber combat. Over the course of the Clone Wars, Grievous' shrewd battle planning and ruthlessness caused him to become feared throughout the Galactic Republic. Grievous was successful in defeating many of the Republic's Jedi Generals, even going so far as to maintain a collection of lightsabers taken from the Jedi he had slain. He clashed with Padawan Ahsoka Tano and Jedi Master Obi-Wan Kenobi on multiple occasions and quickly developed a rivalry with Kenobi.
Under the command of Grievous, the droid army wreaked havoc across the galaxy. Alongside Dooku's apprentice, Asajj Ventress, Grievous led the assault on Kamino in an effort to halt the production of the Republic's clone troopers. Although unsuccessful, the mission saw Tipoca City's cloning facilities suffer major damage, striking a critical blow to the Republic. Later, at the behest of Dooku, Grievous traveled to Dathomir where he confronted the clan of mysterious witches known as the Nightsisters. The sisters were completely wiped out in the subsequent massacre, save for a now-disgraced Ventress and their leader Mother Talzin. Then, following the reemergence of the fallen Sith Lord Darth Maul, Grievous engaged him during his quest for revenge against his former master, Darth Sidious. Grievous was able to force the Zabrak's retreat, finally kill Talzin and effectively dissolve Maul's deadly Shadow Collective.
Near the end of the war, Grievous launched an attack on Coruscant and successfully captured Supreme Chancellor Palpatine. There Palpatine, secretly Grievous' master, Darth Sidious, was held aboard the general's flagship, the Invisible Hand. However, after the death of Count Dooku at the hands of Jedi Knight Anakin Skywalker and the crippling of his flagship, Grievous was forced to retreat and relocate to the remote Outer Rim world of Utapau. Palpatine leaked his location to the Jedi High Council, who dispatched Obi-Wan Kenobi to find and kill the general. Kenobi arrived in Pau City, a mining settlement in an Utapaun sinkhole, where the Jedi challenged Grievous to a duel. Following a haphazard chase through the city streets and a brief brawl on a landing platform, Kenobi opened fire on Grievous' organ sack with the Kaleesh's own blaster, resulting in the dreaded cyborg's demise.