No one is quite sure who Grievous was before he became a cyborg, or what caused him to make the transformation, but what is known is that Grievous was one of the most imposing figures in military history. His first appearance was when he attacked and killed Daakman Barrek and his apprentice Sha'a Gi during their mission on Hypori. Barrek was able to transmit a message to Jedi Master Obi-Wan Kenobi. With his existence being exposed, he led many more assaults on other worlds, eventually conquering the entire Corellian Trade Spine, striking fear in the hearts of the residents of Core Worlds. Their worst fears were realized, when Grievous sent an attack force to Coruscant itself, capturing Supreme Chancellor Palpatine. During the insuing battle, he was killed in a lightsaber duel by Obi-Wan Kenobi.