Doulos

Doulos is the name used for the type of associated intelligence in service to the Forsaken, a covenant remnant faction. During the time of the Covenant, research into AI was restricted by the penalty of death but only the simplest of intelligence was allowed to exist, barring on non-sentient.
While research into AIs was illegal, High Kaidon Garr 'Alakavai during his time as a Fleet Master would establish a secret facility to conduct such research with a select few, including his friend Khito 'Nucam.
A semi-sentient associated intelligence called Doulos had entered service in a variety of different roles within their society from combat drones to starship turrets shortly after the official founding of the Forsaken. They originate from the UNSC dumb AI Macoun who was captured by 'Nucam early in the Covenant War and experimented upon by loyal Huragok.