the prophits

San 'Shyuum (Latin Perfidia vermis, meaning "Worms of Treachery"), also known as Prophets, are a mammal-like species who are the leadership caste within the Covenant and one of the more mysterious member races of the hegemony. Prophets appear to exert complete control over religious and political affairs, fulfilling the role of religious and political leaders. Prophets enforce a misguided theology based on the false belief that firing the Halo Array will start the Great Journey transcending them into a God-like status. Although physically frail compared to other Covenant species, they wield absolute power over the Covenant, making them more dangerous than most.I have got this info from halopedia.com