Gravemind

The Gravemind is a parasitic, hive mind intelligence in the Halo universe. While only one Gravemind is ever seen in the games, the title is given to the final stage of Flood evolution, in which the Flood becomes a superorganism. The Flood is a highly-infectious parasite which is released several times during Halo's story. The Chief and the Arbiter (Thel'Vadam, during the course of Halo 2 and Halo 3) are captured during their separate missions on Delta Halo, or Installation 05, by a Gravemind, which resides in the bowels of the ancient Forerunner ringworld, where the Flood creature forges an alliance between the two foes in order to stop the activation of the ringworld — an event which would destroy all sentient life, and, therefore, starve the Flood. The character is voiced by Dee Bradley Baker.