The Z-1500 Automated Systems Drone, also known as a Sentinel Drone and by the Covenant as "Holy Warriors of the Sacred Rings," is a broad category of Forerunner-constructed robots designed to suppress Flood outbreaks, construct and maintain Forerunner structures, mine and retrieve raw materials, and protect Forerunner technologies from alien lifeforms. To this end, they possess limited artificial intelligence and boast a wide range of weaponry and equipment in the field.

Overview & Background

Following the construction of the Halos, Sentinels were built to serve as the first line of defense against Flood outbreak and external intrusion. The non-organic composition of the Sentinels allowed the Forerunners to battle the parasite without contributing to its numbers. Controlled by their own autonomous AI and their Installation's Monitor, Sentinels patrol the Halo rings and destroy anything deemed to be a threat.


Sentinels are grayish-white in color and have two arm-like appendages with two grapple fixtures at the end of each arm, along with a central "head" and a curved undercarriage containing a Sentinel Beam. The form of a Sentinel may differ depending on the situation of their Installation. Their powerful offensive beam weapons and defensive energy shield make them very effective in combat against intruders or foreign objects that present themselves as threats. Their smaller lasers are used for both repairing damaged Forerunner constructs, and self-repair should the Sentinel be damaged in combat. Sentinels are propelled by both an anti-gravity unit located on the undercarriage and small engines on the back of the unit. They are capable of traveling at high speeds but cannot sustain long range travel.

Sentinels are created at Sentinel Production Facilities, massive floating platforms that are located on every Halo Installation. These Facilities produce all types of Sentinels when facing either a Flood outbreak or an external threat to a Halo Installation or Construct. These massive assembly lines at maximum performance can produce Sentinels at a very fast rate to either supplement existing Forerunner defenses or to replace those destroyed for whatever reason. Sentinel Production Facilities are not limited to just the Halo Installations, Production Facilities are located on every Forerunner Construct that relies on Sentinels for guarding, although these facilities are different in appearance and may be either ground or mobile based platforms.

Gameplay Information


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Sentinel Sniper

Main article: Sentinel Sniper

A black colored variant of the standard Sentinel with blue lights but armed with the Sentinel Sniper Beam instead of the regular Sentinel Beam. They are commonly seen withing groups instead of by themselves


Main article: Enforcer

Essentially heavy Sentinels, Enforcers are equipped with a variety of offensive and defensive weaponry, including Pulse Beams, Missile Projectiles, Sentinel Beams, and dual Energy Shields covering both their top and bottom halves. They are designed to handle major Flood outbreaks but are also capable of defending their Halo Installation from external threats.

Developer Information