The Piraka was the name adopted by a group of six Skakdi ex-Dark Hunters which broke away from that organization and attempted to steal the Kanohi Ignika. They were Zaktan, Hakann, Avak, Reidak, Thok, and Vezok. Vezon was unofficially considered a seventh member.
With their devastating eyebeams and zamor sphere launchers, the Piraka were a serious threat. The Piraka were once members of a shadowy organization called the Dark Hunters. The Piraka's zamor spheres contained the antidermis virus, which could enslave others. There was a mysterious seventh Piraka named Vezon.
In the Matoran language, the word Piraka meant "thief," among other things, although it meant much more than that as well. A common thief might sneak into a village to steal something of value; a Piraka would set the whole village ablaze to cover up his theft. A robber would normally make an effort to slip in and out unnoticed; a Piraka would destroy whatever or whoever was in sight, purely out of spite. Piraka were criminals, looked down upon even by other criminals, as scum. Calling someone by that name had the potential to start a violent, centuries-long feud. There were few words more vile that an intelligent being could utter.
The Piraka were Skakdi from Zakaz. According to the Order of Mata Nui, they were the six most infamous examples of the negative, violent tendencies of their race.
Piraka was a Matoran term meaning "thief and murderer."
The Piraka used Zamor spheres filled with antidermis, a virus used to enslave the Matoran (and, unknown to all, the very essence of Makuta).
The Piraka wanted the Mask of Life for their own personal power.