This Grunt is found cowering on the edge of a cliff right before the player goes down the ramp to leap into UNSC Forward Unto Dawn's hangar in the level Halo in Halo 3. As the player reaches a white rock arch, turn the vehicle slowly to the right and a narrow pathway will be visible. At the end of the pathway is the Grunt. If the player approaches him, he will start speaking.
Discovering the Final Grunt may leave the player unable to complete the end of the level as the platforms would have broken apart, thus rendering no possible route available to reach Forward Unto Dawn.