Jiralhanae Bodyguard
From Halopedia, the Halo wiki
The Brute Bodyguard is a Brute (Jiralhanae) rank/specialty [1]. They are responsible for the protection of their tribe's Chieftain, they are also responsible for the enforcement of tribal law. Whenever there is a Chieftain nearby, you will encounter Brute Bodyguards which look very similar to Captain Ultras. Bodyguard Brutes are also seen to be protecting Truth on the level The Covenant.