Sentinel

This is about the Forerunner constructs. For the UNSC AI type, see Navy Sentinel. For the achievement, see Sentinels (achievement).

An Enforcer flanked by two Aggressors.

Sentinels are autonomous machines created by the Forerunners, designed for the construction, maintenance and defense of their structures and facilities. Various Sentinel variants exist, each tailored to a specific task; because of its ubiquity, the Aggressor variant is often referred to simply as the "Sentinel". All variants are produced by Sentinel manufacturing facilities. The Sentinels were revered by the Covenant as "holy warriors of the Sacred Rings".

The Sentinels follow the command of the monitor or other ancilla that is in charge of the facility they are assigned to, but even without central direction, they are able to respond to threats against their assigned installations with remarkable coordination and effectiveness. Sentinels follow their directives even if this entails engaging other Forerunner machines. For example, the Aggressor Sentinels of Requiem remained loyal to the Librarian against the Didact's Prometheans in 2557. Another instance is when the Constructors of Genesis remained loyal to Monitor Exuberant Witness against the Created's Promethean forces in 2558.

Types of Sentinels

Aggressors

Main article: Aggressor Sentinel

The Aggressor is the most common form of Sentinel, designed for the protection of Forerunner constructs and the small-scale suppression of Flood forms. There are many forms of Aggressor, though most follow the same basic layout. In the event of a severe threat, an advanced version of the Aggressor would be dispatched to assist the more common Aggressors.

Assembler

Main article: Assembler Sentinel

Assemblers are presumably used to build and maintain Forerunner installations and technology, like the similarly named Constructors. Though they are not designed for combat, they will suspend their primary duties and engage Flood forms in the event of an outbreak.

Automated Turret

Main article: Forerunner automated turret

These turrets are portable can can be deployed.

Constructor

Main article: Constructor

The Constructors are specialized Sentinels, designed solely for the construction and servicing of Forerunner structures. Like Assemblers, they are not designed for combat, but they will engage the Flood if necessary.

Council Sentinel

A special variant of Sentinel was used aboard the Forerunner Capital for security purposes. They possessed black armor, matching the black-and-red armor of Ecumene Council security personnel.

Enforcer

Main article: Enforcer

The Enforcers are equipped with a variety of offensive and defensive measures, including pulse beams, missiles, a last-resort Sentinel beam, and three frontal energy shields. They are designed to handle major Flood outbreaks, but are also capable of defending their Installation from other external threats.

Gatherer

Main article: Gatherer

Gatherers seem to be deployed exclusively on Line installations, and serve as collectors of biological specimens for the resident Monitor. They have offensive capabilities similar to Aggressors.

Protector

Main article: Protector Sentinel

Roughly similar in appearance to regular Aggressors, Protectors are modular units capable of being modified into one of three variants: Offensive, which is a weaker version of the standard Aggressor; Shield, which projects an energy shield around its host unit; and Healing, which provides medical assistance to its host after combat.

Retriever

Main article: Retriever Sentinel

The Retrievers, otherwise known as the Strato-Sentinels, are massive terraforming machines, used to gather raw materials for large-scale Forerunner astroengineering projects such as the Halo Array.

Onyx Sentinel

Main article: Onyx Sentinel

Onyx Sentinels both guard and make up the artificial planet of Onyx. With a much more powerful individual energy beam, as well as the ability to combine and transform themselves in order to complete a specific task. Onyx Sentinels are far more formidable opponents than their more standard variants.

Safeguard

Fitted with powerful sterilization beams, the Safeguard Sentinels are highly efficient at containing and cauterizing intrusions into their assigned protectorate.

Super Sentinel

Main article: Super Sentinel

Considerably larger than Aggressors, Super Sentinels fill the same role as the Enforcers - combating large-scale Flood outbreaks.

Unidentified Sentinel variant

Main article: Unidentified Sentinel variant

The largest Sentinel variant seen to date, this Sentinel is able to level entire cities with its weaponry.

Watcher

Main article: Promethean Watcher

The Watcher is a Sentinel variant used by Promethean Knights for combat support. They can heal and augment their damaged allies and return incoming ordnance such as grenades using a gravity-displacement beam.

List of appearances

• Halo: Combat Evolved (First appearance)
• Halo: The Flood
• Halo 2
• Halo: Ghosts of Onyx
• Iris
  • Halo 3: The Cradle of Life
• Halo 3
• Halo Wars
• Halo Legends
  • Origins
• Halo: Blood Line
• Halo: Cryptum
• Halo: Glasslands (Mentioned only)
• Halo: Combat Evolved Anniversary
  • Terminals
• Halo: Primordium
• Halo 4
  • Spartan Ops
• Halo: Silentium
• Halo: Spartan Assault
• Halo: Escalation
• Halo: Broken Circle
• Halo 2 Anniversary
• Halo: Spartan Strike
• Halo: Hunters in the Dark
• Halo: Last Light
• Halo 5: Guardians
• Halo Mythos
• Halo: Fractures
  • Promises to Keep
• Halo Wars 2