Dweller is one of the villains that appeared in the BIONICLE series. He is also the member of the Dark Hunters as he worked for them as the assassin who have the ability to scan the other beings' minds as well as filling their minds with nightmares, which then drove them insane and used his mental attacks to kill his victims.
Dweller appears as the bat-like hybrid being. He also have a black chest plate, several silver armors fitted on his body and have two pairs of razor-sharp wings. Dweller also have a bat-like head with two red eyes. He also have two sharp talons on his feet.
Not much was known of Dweller's past, but it was once revealed that he once worked for the Dark Hunters as the assassin as he was tasked with the missions of assassination and he also used his mental abilities to kill his targets.
Later, The Shadowed One sent Dweller on a permanent assignment to Metru Nui after the Great Cataclysm to watch over the developments there, as the city was a key tactical location to both the Dark Hunters and the Brotherhood of Makuta. When he finally got there, Dweller used his powers to monitor events, and periodically sent out a Rahi with reports to the Shadowed One. He also used his power to hid himself from discovery from anyone who wandered inside the tunnels where he lived, such as the Rahaga. During his time at Metru Nui, he witnessed and reported the battle between the remaining group of Visorak and the alliance of Turaga Dume, Toa Hagah and Keetongu. He then entertained himself by giving Norik nightmares about the Visorak and Dark Hunters conquering Metru Nui.
Later, Dweller returned to Odina and report all the events to the Shadowed One.
Following Mata Nui's revival and during the Brotherhood of Makuta's invasion, the Shadowed One ordered Dweller to follow Takanuva and strike him when he was vunerable, opening the way for the Dark Hunter invasion. Soon after, Dweller hid himself in Le-Metru and attempted to probe Takanuva with his mental power following his arrival to Metru Nui but Takanuva sensed his presence