Titan

"Titan" was a former Dark Hunter and later became a servant of the Brotherhood of Makuta.

Dark Hunter
After being recruited by "The Shadowed One," Titan hunted many Toa. But one day, Toa Bounty Hunter beat him in finding Toa Pontias. Therefore "The Shadowed One" had to execute Titan because of Titan's failure and his own anger against Toa Bounty Hunter.

So Titan decided to run away before the execution date. He broke from prison and escaped to the Brotherhood of Makuta's base, which was the only place he could find safety from the Dark Hunters.