"Subterranean"

"Subterranean" was a former Onu-Matoran and Dark Hunter.

Toa\Dark Hunter War
Many centuries ago, when the Toa/Dark Hunter War was still raging on, an Onu-Matoran was helping to build a new section of the Archives under Ga-Metru when the tunnel ceiling collapsed. What exactly happened to the Matoran is shrouded in mystery, but it is possible that there were mutagenic chemicals in a Ga-Metru laboratory above the dig site, which poured all of its contents onto him when it caved in and mutated him into his current state.

Dark Hunter
After escaping from the tunnel, his new form scared his friends, and in grief he left the city with the Dark Hunters, as they were expelled from the city after the war. He is currently trying to arrange an alliance between the Hunters and a tribe of Frostelus on the grounds that he is one of the few creatures uglier than they are.

Powers and Abilities
"Subterranean" could disassemble objects by touching them, and could immobilize enemies just by looking at them. His major weakness was sound, as even the slightest whisper was painful to him; he wore special armor that dampened sound to compensate. Still, "The Shadowed One" stated that he tries to avoid a Toa of Sonics (possibly Krakua), who has the potential to kill him, as much as possible.