M5-BZ, also referred to as simply BZ or Beezee, was an astromech droid who had served the Jedi Master Tera Sinube and subsequently became a member of D-Squad. M5-BZ was lost in hyperspace after opening an airlock while aboard a Venator-class Star Destroyer, the Renown.
Gascon inside BZ's head.
M5-BZ served the Jedi Master Tera Sinube. When Colonel Meebur Gascon of the Galactic Republic wished to infiltrate a Separatist ship in order to obtain an encryption module scrambling all Separatist communications within the region, he formed D-Squad, an all-droid team. M5-BZ was assigned to the team, but the droid secretly had his memory banks removed, allowing the diminutive colonel to use him as a mobile command center.
While on this mission, M5-BZ tried to open a booby-trapped door, and got electrocuted. The rest of his team repaired him shortly afterwards.
While on a mission, D-Squad came under attack by a swarm of buzz droids aboard a Venator-class Star Destroyer, the Renown, which had been captured by the Separatists, and M5-BZ opened the ship's airlock, pulling the buzz droids, along with himself, into the vacuum of space.
M5-BZ was remembered as a hero for his actions of his sacrifice to save D-Squad, and Gascon gave an impromptu eulogy speech before the squad continued their mission and eventually prevented the destruction of the Valor space station.
M5-BZ first appeared in "Secret Weapons," the tenth episode in season five of Star Wars: The Clone Wars.