Tayuka

History
Tayuka's favorite thing to do was terrorize matoran. He decided to move up a level to terrorize toa. In BIONICLE: A Secret Savior, he is only found in karda nui. Toa Auga finally finds him after searching and finds a way to kill him. Because he is not known, the story is called a secret savior

Personallity
He is a cold-blooded beast killing everything in his way (even his own teams shadow matoran if they slow him down)