Editing Aggressor Sentinel

{{Status|Canon}}

{{Disambig header|the standard and common sentinel introducted in ''[[Halo: Combat Evolved]]''|the gold-colored variant introducted in ''[[Halo 2]]''|Aggressor Sentinel Eliminator}}

|role= Combat and defense

|length={{Convert|9.6|ft|m|sp=us|disp=flip}}{{Ref/Reuse|h4evg}}

|width={{Convert|6.3|ft|m|sp=us|disp=flip}}{{Ref/Reuse|h4evg}}

|height={{Convert|5|ft|m|sp=us|disp=flip}}{{Ref/Reuse|h4evg}}

|armament=[[Sentinel beam]]

|armor=[[Energy shields]]

'''Z-1500 Automated Systems Drones''' ('''Z-1500 ASD'''),<ref name="h4evg">'''[[Halo 4: The Essential Visual Guide]]''', ''page 133''</ref> more commonly known as '''Aggressor Sentinels''',<ref name="EVG">'''[[Halo: The Essential Visual Guide]]''', ''page 167''</ref> are [[Forerunner]] automatons programmed to act as security and maintenance drones, suppress small-scale [[Flood]] outbreaks, and protect Forerunner installations. As the basic type of the fairly inclusive [[Sentinel]] class, Aggressors are generally referred to simply as '''Sentinels'''.{{Ref/Reuse|EVG}}

==Design details==

[[File:H2-ThreeSentinelAggressors.png|250px|left|thumb|Three [[Aggressor Sentinel Eliminator|"Eliminator" Sentinels]], as shown by their gold chassis.]]

Aggressor Sentinels have two arm-like appendages, with two fine manipulators at the end of each arm. Their central head rests above a curved undercarriage housing an offensive [[Sentinel beam]]. Their powerful beam weapons and defensive energy shields 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 in conjunction with [[Constructor]]s, and self-repair should the Aggressors be damaged in combat.{{Ref/Reuse|encyclopedia}} Aggressors are propelled by both an anti-gravity unit located on the undercarriage and small, exotic form of [[impulse drive]] which enables them to travel at high speeds.{{Ref/Reuse|h4evg}} They are also capable of tapping into their installation's [[teleportation grid]].{{Ref/Reuse|h4evg}}

There are at least two variants of the Aggressor Sentinel; the most common model is grayish white in color while the specialized model is golden. The differences between the two variants lie solely on their offensive and defensive systems; the gold-colored version sports superior weaponry and shielding system to the common grayish-white model's.

Aggressors are created at [[Sentinel manufacturing facility|specialized manufacturing facilities]],{{Ref/Reuse|encyclopedia}} massive airborne platforms that are located on every Halo installation and on other key Forerunner installations such as [[shield world]]s. These compounds produce Sentinels when facing either a Flood outbreak or an external threat to their local installation. The 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.

[[File:H3_Sentinel_Shielding.jpg|thumb|right|250px|A Sentinel's energy shield.]]

Aggressors were utilized as all-purpose workers and guards on Forerunner stations. Following the construction of the [[Halo Array]], they were reconfigured to be the first line of defense against Flood outbreaks and other external intruders. The mechanical nature of the Aggressors make them ideal combat units against an enemy that could convert conventional biological infantry into biomass - by deploying the Aggressors en masse, the Forerunners could battle the parasite without contributing to its numbers. Controlled by their own basic AI functions, as well as their installation's [[monitor]], Aggressors patrol the installation's vast terrain and network tunnels tirelessly and attack as their protocol demands.<ref name="encyclopedia">'''[[Halo Encyclopedia (2009 edition)]]''', "Chapter 8", ''page 226-227''</ref>

When not in combat Aggressors serve as basic repair, maintenance, and security drones for Forerunner installations and facilities where Flood samples are kept, working in conjunction with [[Constructor]]s and [[Enforcer]]s to ensure that the facility remains in working order.

The [[Forerunner Dreadnought]], the [[San'Shyuum]]'s [[keyship]], was equipped with its own contingent of Sentinels. The San'Shyuum managed to adapt these machines to serve them in a combat support role. Aggressors under San'Shyuum control were used in battles during the [[War of Beginnings]] before the [[Covenant]]'s formation.<ref>'''Halo: Broken Circle''', ''pages 6, 9''</ref> The war depleted the Sentinels' numbers almost completely and the few that remained in ''[[High Charity]]'' were regarded as relics to be preserved and were no longer used in combat.<ref>'''Halo: Broken Circle''', ''page 189''</ref>

[[File:H2A FirinMahLazer.png|thumb|225px|left|An Aggressor firing its [[Sentinel beam]].]]

Aggressors are the first Forerunner automated defense systems to assist a in a given situation and generate a proper response protocol. While Aggressors are strong enough to handle small-scale battles, they are more of a supplement rather than a reliable combat system. The Aggressors' weapons systems are limited and not as powerful as some of the other Forerunner weapons employed against the Flood, and can only hold them at bay for a limited amount of time.  

Because of their limited AI, they are only individually able to handle situations on a basic scale, which makes them vulnerable to strategic Flood attacks. Because of their limited intelligence they are not often able to perform evasive maneuvers when facing imminent attack and are usually destroyed. In overwhelming numbers, Aggressors are capable of impressive coordination and are more than capable of handling a situation for a certain time until more permanent measures can be applied.

 

[[File:HW2-Sentinel bombardment.png|thumb|250px|right|Thousands of Aggressors swarming the ''[[Enduring Conviction]]''.]]

*'''[[Aggressor Sentinel Eliminator]]''': This variant acts just like an average shielded Aggressor Sentinel, but has more durable gold-colored armor, faster recharging shields and utilizes a stronger blue Sentinel Beam. This variant was deployed during the Flood-outbreak on [[Installation 05]]. A different version armed with the [[Heatwave]] was deployed during the [[Installation 07 conflict]].

File:HINF EliminatorCrop.png|Aggressor Sentinel Eliminator.

*'''[[Sniper Sentinel]]''': This variant is similar to an Aggressor Sentinel without arms, and wields a [[Shock rifle]]. This variant was deployed during the [[Installation 07 conflict]].

File:HINF SniperSentinelCrop.png|Sniper Sentinel.

There are several major designs of "standard" Aggressor Sentinel that additionally exist.

File:H3-SentinelAggressor.png|A chassis of the Aggressor Sentinel deployed during the [[Battle of Installation 00]] and [[Raid on Installation 08|Installation 08]].

File:H4 Sentinel.png|A chassis of the Aggressor Sentinel deployed during the [[Battle of Installation 05]] and [[Battle of Requiem|Requiem]] and the [[Second Ark Conflict]].

File:HINF SentinelCrop.png|A chassis of the Aggressor Sentinel used during the [[Installation 07 conflict]].

[[File:AggressorSentinelEvolution-RefChart.jpg|thumb|350px|Evolution of the Aggressor Sentinel's design throughout the ''Halo'' games.]]

* Sentinels are more expressive in their muteness, and will tilt and move their arms in various situations.

* There are three variants of sentinels: the basic gray one armed with a Sentinel beam, a 'sniper' sentinel with a 'cross' silhouette and armed with a [[Shock rifle]], and the golden variant protected by an energy shield and armed with the [[Heatwave]].

* Sentinels are weak to shock weapons, and take more damage when shot in their eye.

* Sentinels are not hostile to [[Banished]] forces, and can be seen collaborating with them.

Aggressors appear in both campaign and Skirmish mode of ''Halo Wars'', serving as an air unit. In campaign, Aggressors are the primary Forerunner unit, appearing on levels set within the [[Etran Harborage]]. Like all Forerunner units, they are hostile towards all three other factions, including UNSC, Covenant, and the Flood. They are produced from invisible spawn points that could not be targetted or destroyed.

Aggressors Sentinel are normally a hostile unit, but [[Professor Anders]]' upgrade for the Protector Sentinel allows Aggressor Sentinels to be its escort. Aggressors have a smaller version known as the Sentinel Swarm, which  is impervious to most attacks, except when struck by an EMP MAC or the Aggressor Sentinel coordinating it is destroyed.<ref>'''Halo Wars 2''', Campaign level ''[[The Cartographer]]''</ref><ref>'''Halo Wars 2''', Campaign level ''[[Gatecrashers]]''</ref> On the skirmish map, a group of three Aggressors can be seen guarding a Power Node and it has the ability to de-capture the Power Node should anyone takes control of it while the Aggressors is around. In Skirmish, Professor Anders can utilize her leader power '''Ark Defense''' and ''Sentinel Beacon''' to spawn the Aggressors Sentinel to draw the anti-air aggro.

*Chris Hughes created the original concept art of the Sentinel.<ref>'''[[The Art of Halo]]''', ''page 44''</ref>

*In the ''[[Deliver Hope]]'' trailer, the shielding on the Covenant {{Class|CCS|battlecruiser}} appears similar to the energy shields on the Aggressors in ''[[Halo 3]]''.

File:HINF Concept SentinelSwarms.jpg|Early ''Halo Infinite'' concept art depicting [[John-117]] observing swarms of Aggressor Sentinels on Installation 07.

File:Sentinel-OrthoSchem-scantransparent.png|An overview of the Aggressor Sentinel in ''[[Halo Wars]]''.

File:Halo4-CarbineScope-SentinelAttack.jpg|Sentinels attacking a [[Mgalekgolo|Hunter]], as seen through the scope of a [[Type-51 carbine]] wielded by John-117.

File:H2A Aggressor.png|A side view of the Sentinel.

File:H2A SentinelBois.png|Two Aggressors alongside a Constructor.

File:HW2-sentinels.jpg|A swarm of Aggressors in formation.

File:HINF SentinelScan.png|Aggressors scanning the wreckage of a {{Class|Mulsanne|light frigate}}.