The Grunt Rebellion is an event in the history of the fictional alien empire of the Covenant in the video game Halo: Combat Evolved.

The Grunt Rebellion was an event dangerous enough to the Covenant that an Arbiter had to be created to combat it. Like all the other Arbiters, it is assumed that the Arbiter at the time died in the course of the Rebellion. The only other thing known is that it involved the smallest and most common form of the Covenant, the Grunts, rebelling against the rest of the Covenant.

Because the majority of the warriors and workers of the Covenant appear to be these 5 foot tall aliens, this event would have been extremely hard to deal with. We do not know when the Grunt Rebellion took place, but it is a famous event in the History of the Covenant sometime in the earlier history of the Covenant, possibly in the Ages of Doubt or Conflict.