Vultraz

Vultraz was one of the villains in the BIONICLE series as well as the main antagonist in the side story, Brothers in Arms. He is a malevolent and treacherous Ta-Matoran of the Tren Krom Peninsula before he became the Shadow Matoran who later worked as the servant of the Brotherhood of Makuta. He was also responsible for the death of Mazeka's mentor, which caused the latter to hunt him down.

History
Vultraz was a Ta-Matoran who lived on the Tren Krom Peninsula as he gained his reputation as a criminal. He also killed Mazeka's mentor to steal is research, which included the theories about how the Great Beings created the Makuta species, and later murdered the entire village to obtain the rare lava-gem. His actions eventually led Mazeka to wish to bring him to justice and as the result the two clashed in many occassions. Five years later, Mazeka managed to defeat Vultraz by kicking him over the cliff, where the Ta-Matoran seemingly fall to his death.

Working for the Brotherhood of Makuta
Vultraz was happened to survive the fall but he was heavily damaged. He was then saved by a Rahi sent by Gorast, a female Makuta who worked for the Brotherhood of Makuta. She then rebuilt him so that he would no longer be recognizable

Trivia

 * Vultraz was considered as one of the darkest villains in the BIONICLE series alongside Makuta Teridax, Roodaka, Pridak, Umarak, and Karzahni.
 * He was one of the Matoran that served as the villain alongside Ahkmou, Radiak, Gavla, Kirop and Vican. However, Ahkmou himself was not one of the Shadow Matoran.
 * Vultraz's mask was also similar to Icarax's Mask of Scavenging and Kalmah's head.