The Prophets are the generals of the Covenant, but are rarely seen fighting in battle.  The Prophets are the ones that are leading the campaign against the humans.

Grunts, Jackals, and Drones are the basic infantry units for the Covenant.  Grunts are very weak and are the lowest rank in the Covenant army.  Grunts normally travel in packs of three or more.  When you are fighting a solitary Grunt they will run away in fear.  Jackals are the snipers of the Covenant army.  They hide behind a large shield while shooting you which makes it very hard to hit them with a shot.  Jackals are higher in rank than Grunts and drones but are still very weak.  Drones can be hard to kill and also a nuisance because they can fly and are very fast.  Drones are very smart strategists and are excellent shots.  Despite all of this they have one major weakness:  They can be killed in only one or two shots.

Elites, Brutes, and Hunters canal be very difficult to kill.  The Elites are the core of the Covenant military.  They are often seen leading groups of Grunts and can use many different types of weapons.  They are smarter, faster, and stronger than humans which can make them very dangerous.  The color of their armor normally indicates their rank.  Brutes are physically stronger than elites and are about the same rank.  They travel together as packs and have much more powerful melee attacks than elites making them very problematic.  Hunters are the strongest and most dangerous warriors in the Covenant army.  They have impenetrable armor, a devastating hand held weapon built into their right hand, and a shield to hide behind built into their left hand.  They are both stronger and faster than Elites and Brutes but are not as high of a rank as them.  Hunters are usually found in pairs in heavy defensive positions.