M5-BZ, also known as BZ or Beezee, was an astromech droid who initially served under the command of Jedi Master Tera Sinube before later becoming a member of the group known as D-Squad. Following the opening of an airlock while he was on the Venator-class Star Destroyer called the Renown, M5-BZ was lost within hyperspace.
The Jedi Master Tera Sinube was once served by M5-BZ. Colonel Meebur Gascon of the Galactic Republic desired to get inside a Separatist ship to acquire an encryption module that would scramble all Separatist communications in the area. To do this, he put together D-Squad, a team made up entirely of droid units. M5-BZ was selected to join the team, but without his knowledge, his memory banks were taken out, which allowed the small colonel to utilize him as a mobile command post. M5-BZ attempted to open a booby-trapped door during this mission, which resulted in his electrocution. Shortly after, the rest of his crew fixed him.
While they were on a mission, D-Squad was attacked by a group of buzz droids while aboard the Renown, a Venator-class Star Destroyer that the Separatists had taken over. M5-BZ then opened the ship's airlock, which pulled the buzz droids and himself into the vacuum of space.
M5-BZ was remembered as a heroic figure because of his self-sacrifice to save D-Squad. Before the squad moved on with their assignment and ultimately stopped the destruction of the Valor space station, Gascon gave an impromptu speech in his honor.
Industrial Automaton produced M5-BZ, who was a R4-series astromech droid. He had black sensors and was 1.15 meters (3 feet, 9 inches) in height. BZ's memory was removed to make room for Colonel Meebur Gascon's mobile command center. He later gave his life to protect Gascon and the rest of D-Squad from buzz droids.
The first appearance of M5-BZ was in "Secret Weapons," which was the tenth episode of Star Wars: The Clone Wars during season five.