Muzzle was a clone trooper with a defective genetic makeup, who functioned as an Advanced Recon Commando throughout the Clone Wars for the Grand Army of the Republic. He ultimately deserted, subsequently becoming the leader of the mercenary group known as the Aurodium Sword, which often took on assignments to protect Galactic Republic corporate figures, for example, Raith Sienar.
Within the current Star Wars canon, Muzzle received a mention in Collapse of the Republic, a 2019 addition to the Star Wars Roleplaying series from Fantasy Flight Games. In Star Wars Legends continuity, Muzzle was initially introduced as Alpha-66 in the "Underworld: A Galaxy of Scum and Villainy" article, which was written by Abel G. Peña and Ryan Kaufman and appeared in Star Wars Insider 89 in 2006.