Regicide (Full name: Regicide Crystax Matrix) (Japanese version 国王殺し Kokuō Koroshi), alias Knight Matrix, is a Matrix Pyrus Bakugan and a Bakugan of the Matrix Six. Regicide is also the main Matrix Pyrus Bakugan in the Matrix Dimension.
Regicide is a hot-headed Bakugan, but is usually seen as a calm and collected one around others, similar to his older brother Simulacion. Regicide looks up to Simulacion like a role model, and respects his brother, who does the same in return. Regicide is energetic and very thoughtful of others, particularly his sisters, who he watches out for. He is a good leader, despite the fact that he is a second in command of both the Matrix Six and the Matrix Siblings. Despite the fact that he is a normally peaceful Bakugan, Regicide, as his name suggests, will gladly commit it in order to destroy any evil forces he comes across. He is seen as the most heroic Bakugan of the Matrix Six and of the Matrix Siblings.