Mandroxa

Ranked as XV in Organization XIII, he is the Organization's third member to wield both the keyblade and the power of light. He resides with the group in Minipeg, as the self proclaimed leader of the Final Seven.

Origin
Mandroxa was inducted into Organization XIII at the same time as Xthanan when they were found by Xigbar.

Key Plot Points
Mandroxa lost his heart after he tried to save Xthanan from a Mad Dog Heartless. His sacrifice to save his friend proved to be futile, as Xthanan also lost his heart and the two became nobodies. They are soon after inducted into Organization XIII.

Xemnas realises Mandroxas' potential as a Keyblade Wielder, and Xigbar trains him to use his power.

Mandroxa and Xthanan are told to search their world for additional nobodies to induct into the Organization while fighting Heartless and collecting hearts. To ensure that nothing prevents Mandroxa from completing his tasks, Xemnas soon cuts the original members off from Mandroxa and the newer members.

After he is separated from Xthanan for a period of time while scouting Molson School, he happens upon Xfrestro.

After the Corridor of Darkness opens to Eldonan Mast Collegiate, Mandroxa spends many periods of time looking for his younger brother.