RB-551 was an older model of the B1 battle droid that was controlled by a central computer rather than being a free-thinking droid such as the newer model. He served the Confederacy of Independent Systems during the Battle of Ryloth. His head was discovered by a droid patrol on the flatlands of Cazne, where he, along with other battle droids was destroyed by the Free Ryloth movement.
- (First mentioned)
- Star Wars: The Clone Wars The Complete Season One