A Parallel Universe was a separate reality of the main BIONICLE Universe, with minor and major differences.
Known Universes
"Toa Empire" Parallel Universe
See main: "Toa Empire" Parallel Universe
In this parallel universe, Toa Tuyet, using the Nui Stone, allied with Toa Nidhiki to kill Toa Lhikan. Tuyet proceeded to blame the deaths of Matoran she killed to appear like a countdown on the Dark Hunters and organize Toa across the Matoran Universe into the Toa Empire with herself as Empress. Corrupting her Empire, she eliminated organizations she believed posed a threat to Mata Nui, primarily the Brotherhood of Makuta.
"The Kingdom" Parallel Universe
See main: "The Kingdom" Parallel Universe
In this Parallel Universe Matoro hesitated for one second too long and failed to save Mata Nui.
"Journey of Takanuva" Parallel Universe
See main: "Journey of Takanuva" Parallel Universe
In this Parallel Universe Kanohi can talk and Rahi are intelligent and run there own land
"The Melding" Parallel Universe
See main: "The Melding" Parallel Universe