Jiralhanae

The Jiralhanae (Latin, Servus ferox, translated to "wild slave"), known by Humans as Brutes, are a carnivorous sapient species of pseudo-ursine mammals. Originating from the planet Doisac, the Jiralhanae were the final addition to the Covenant hegemony. They have a profound hatred of the Sangheili, unmatched by any other feud within the Covenant, fueled by the Jiralhanae's naturally aggressive demeanor and the Sangheili's natural sense of superiority.

Exceedingly strong (surpassing the strength of both Sangheili and SPARTAN-IIs/IIIs), the Jiralhanae place a greater emphasis on brutality than wisdom and are on the whole a savage species. Preferring this potential for blind obedience, the High Prophet of Truth began plans to replace the Sangheili with Jiralhanae, slowly placing the latter in higher positions and giving them greater allowances than Sangheili troops would receive. Finally, on Truth's orders, the Jiralhanae began a galaxy-wide purge of Sangheili High Councilors and commanders, sparking a cataclysmic civil war known as the Great Schism that led to the dissolution of the Covenant. This civil war would continue well after the end of the Human-Covenant War.

Source

 * Halopedia