In the last years of the Old Republic, the most fearsome of all droid armies was formed by The Confederacy of Independent Systems to rock the very foundations on which the Republic was built. Such an army would require a master of strategy to be effective. General Grievous was that leader. Waging a war of terror across the outer worlds of the Republic, he killed countless members of the clone army used by the Republic and many Jedi in successful campaigns.

Grievous's deadly cybernetic body was created by the engineers of the Confederacy. Little of Grievous's organic body was left making him a creature of metal. Grievous used his cybernetic body to its maximum potential and was renowned for his skill in hand to hand combat. He was capable of taking down Jedi in one on one fight. He would then claim the Jedi's lightsaber as a grisly trophy. One of the defining characteristics of Grievous is his constant wheeze and cough which is the result of a battle with Mace Windu. Windu used the force to crush his chest, badly damaging Grievous.

***Spoilers for Episode III: Revenge of the Sith Follows:***

Grievous Led his assault all the way to the capital of the Republic, Coruscant. He held hostage Chancellor Palpatine, on board his flagship. Obi-Wan Kenobi and Anakin Skywalker were able to infiltrate his vessel and fight there way to where the Chancellor was being held. They then confronted Grievous. Grievous was able to escape from the two Jedi. Later on he was confronted again by Obi-Wan Kenobi attacking Obi-Wan with four Lightsabers he had taken from his previous victims. After a fierce battle Obi-Wan was able to defeat him. After General Grievous's death at the hands of Kenobi, The Confederacy of Independent Systems never recovered from the loss and was soon defeated.

General Grievous makes appearances in Star Wars Episode III: Revenge of the Sith and in the Clone Wars cartoon. General Grievous was designed by Warren Fu after George Lucas gave the direction to his art department that he needed 'a droid general." Fu based his design on a spray bottle he found in his bathroom.

Sources:
http://www.starwars.com/databank/character/generalgrievous/
http://movies.channel.aol.com/feature/starwars/episode_3_video.adp