Arbiter is a fictional ceremonial, religious and political rank bestowed upon alien Covenant Elites in the Halo science fiction universe. In the 2004 video game Halo 2, the rank is given to a disgraced commander as a way to atone for his failures. Although the Arbiter is intended to die serving the Covenant leadership, the High Prophets, he survives his missions and the Prophets' subsequent betrayal of his kind. When he learns that the Prophets' plans would doom all life in the galaxy to extinction, the Arbiter allies with the Covenant's enemies—humanity—and stops the ringworld Halo from being activated. The Arbiter is a playable character in Halo 2 and its 2007 sequel Halo 3; a different Arbiter appears in the 2009 real-time strategy game Halo Wars, which takes place 20 years before the events of the main trilogy.

The appearance of the Arbiter in Halo 2 and the change in perspective from the main human protagonist Master Chief to a former enemy was a plot twist Halo developer Bungie kept highly secret. The character's name was changed from "Dervish" after concerns that the name reinforced a perceived United States versus Islam allegory in the game's plot. (more...)