This is just a stab in the dark, but could the three creatures above be the mysterious SHADOW TOA? On page 18 of the fourth BIONICLE™ comic, it states that the TOA “overcame shadow versions of themselves” after defeating the MANAS, but before defeating Makuta. The SHADOW TOA did not appear in the Mata Nui online game and have not appeared anywhere else, to my knowledge.

Note: The images linked to the three above are larger versions of the ones posted in an earlier article.