"Tahu" could refer to any of the following:
Tahu Stars (Army) - An army led by the infamous Tahu Stars, which currently resides in the Kitchen.
Tahu Stars (Being) - The being responsible for the Civil War, who is currently missing.
Tahu Mata (Army) - The portion of the Bionicles still under the control of Tahu Mata, which currently resides in the Spare Bedroom.
Tahu Mata (Being) - The original leader of the Bionicles, who is currently missing.
Tahu Nuva - A member of Tahu Mata's army and leader of the Toa Nuva.
Tahu Mistika - A member of Tahu Stars' army, who tries not to get too involved in the war. He once (stupidly) tried to take control of the BIONICLEs, but failed.