The Collectors are an enigmatic race that live beyond the Omega 4 Relay, a mass relay within the same system as Omega, in the Terminus Systems. They are rarely seen in Terminus itself, let alone Citadel space, and are generally regarded as a myth by Citadel citizens. Definite sightings of Collectors have been made on Omega every few centuries. They are most well known for their odd trade requests for which they offer new technologies, often of a startling level of advancement. Their requests usually involve the trade of living beings in odd numbers and varieties, such as two dozen left-handed salarians, sixteen sets of batarian twins, a krogan born of parents from feuding clans, or two dozen "pure" quarians — quarians that have never left the Migrant Fleet due to illness, importance to the fleet, or disability. One of their current interests is in healthy human biotics. No one knows what happens to the individuals concerned after the exchange is completed.
The Collectors appear as human-sized bipedal insects with a chitinous exo-skeleton, four eyes, and a distinct, large, tapering head along with fully developed wings that allow them to fly over short distances. Each Collector appears to be little more than a drone with no distinctions between individuals. Although they do not appear to communicate vocally, since none are heard speaking, they have been heard to cry out in pain when shot or killed. While exploring a supposedly derelict Collector ship, Shepard and team discover the true origin of the Collectors. Since they exhibit a similar quad-strand genetic structure unique to the Protheans, Shepard realizes that the race formerly believed extinct still exists but has been completely subjugated by their Reaper masters. Their DNA showed signs of "extensive genetic rewrite" including three fewer chromosomes, reduced heterochromatin structure, and the elimination of superfluous "junk" sequences.
While studying Collector data in the lab aboard the Normandy SR-2, Mordin Solus determines that the Reapers indoctrinated the Protheans and compensated for their growing lack of ability due to prolonged indoctrination through cybernetic modifications. The modifications are beyond any form of repair, each Collector drone being little more than a clone—it's unknown if they even still possess any form of gender—riddled with cybernetics, lacking glands or digestive system, and having any form of intelligence or self-awareness completely eradicated by indoctrination. Periodically, individual Collector drones are "possessed" by an overseer, referred to as the Collector General who subsequently is being possessed by the Reaper known as Harbinger. In effect it is as if Harbinger is assuming control of individual Collectors to combat Shepard personally. Upon possession a Collector's skin and eyes begin to crack open and emit a bright orange light. Bearing a strong similarity to the husk conversion process used by Sovereign on Saren's corpse, this is probably due to cybernetic implants throughout a Collector's body. At this point, the drone becomes more resilient and wields powerful biotic attacks. The Collector General itself is very different to a standard drone, being almost completely insectoid, with a much larger head, a short body, and multiple claw-like limbs.
All known expeditions to investigate the Collectors have failed. No vessel that has ventured beyond the Omega 4 Relay has ever returned. Some speculate that there is a black hole at the relay's counterpart, but this raises the question of how the Collectors can safely use it. Another, rather fantastic, explanation is that on the other side of the relay is a paradise which no citizen of Omega would care to leave due to the crime and suffering of the asteroid. A more likely reason is that the Collectors either detain or destroy any vessels encroaching on their space. Though long believed to be a fringe threat or a myth the Collectors suddenly emerge from the shadows a few months after the geth attack on the Citadel. A lone Collector vessel attacks and destroys the patrolling SSV Normandy, apparently unfazed by the ship's stealth systems. Though much of the crew escaped, Commander Shepard is lost in the attack. Two years later the Collectors reappear as the culprits behind the mysterious mass abductions of human colonies. The Collectors attack their targets without warning, jamming all communications before releasing massive seeker swarms: insectoid probes that paralyze everyone in the colony. After that, the Collectors themselves gather all the paralyzed victims, seal them in stasis pods and depart, leaving no evidence of their presence. They also have hired vorcha to release a bio-weapon plague onto Omega that would have selectively killed all races on the station except humans and vorcha, leaving its human population ripe for the taking. Cerberus is intent on stopping these abductions, especially after realising that there is a Reaper connection to these Collector attacks. The Illusive Man recruits the resurrected Shepard to investigate the purpose behind these abductions. Due to their connection with the Reapers, the Collectors also use husks in their attacks.
When Shepard and team obtain a means to travel safely through the Omega 4 Relay to what is believed to be the location of the Collectors' homeworld near the galactic core, instead, they find a space station, which is the Collectors' base. After traversing through many hazardous obstacles and threats, Shepard and the team infiltrate the Collector base where they discover that the Collectors have been processing tens of thousands of humans they have captured, breaking them down and using them to create a Human-Reaper. EDI theorised that the Reapers tried to use Protheans to create a Prothean-Reaper, but failed. Shepard eventually destroys the Human-Reaper and proceeds to set a countdown which would destroy all Collectors on the base. As the Collector General is about to perish, Harbinger states "You have failed, we will find another way... Releasing control.", revealing that a Reaper was controlling the Collectors all along.
The Collectors themselves are rarely seen since they usually operate through agents, such as the quarian Golo, to make their deals. It has been speculated that the Collectors make these strange requests because of strange fetishes or gruesome culinary tastes. However, it is more likely that they perform genetic experiments on these subjects, possibly testing their viability for use in the creation of a Reaper. Regardless of the possible danger, their requests are often granted by fringe groups because the technology the Collectors offer in return is often extremely valuable, giving any race who receives it an immediate advantage before it becomes adapted to the galactic community.
The Collectors are controlled by a single leader who can possess any member of its species at any time, instantly turning them into the most dangerous Collector on the battlefield. When a Collector is possessed by the leader the outer surface of their body appears to crack open, revealing an orange glow that resembles molten rock.
Upon studying the Collectors, Mordin Solus surmised that the Collectors are in fact mindless drones, "closer to husks than slaves" and lacking any form of culture. He observed that the Collectors show no concern for self-preservation, and will die in battle even if their fight is completely pointless. Believing that culture is impossible without intelligence, he hypothesized that the Collector living areas and bases are completely without any kind of art or creativity. All Collector technology and constructions, he said, exist only for their utility without ergonomics taken into account.
In space, Collectors use the Collector Cruiser for transportation of troops and abducted colonists, while Oculus fighters lay in wait in the Tartarus Debris Field for anyone attempting to investigate the Collectors' source. The bulk of Collector forces consist of Collector Drones; depending on their armament and defenses, these Drones have various titles that designate their general roles in combat. Collector ground troops are supported by seeker swarms that flood battlefields and paralyze victims. Husks and Abominations provide shock troops, while Scions and Praetorians provide artillery and fire support. Collector operations are personally overseen by the Collector General, who is able to command individual Collectors from the safety of the Collector Base and serves a conduit for the Reaper Harbinger.
The Collectors do not engage in direct combat, preferring instead to use "hit and run" tactics. A Collector abduction force usually consists of a single Collector Cruiser carrying many troops and Seeker Swarms. They use the swarms to paralyze their enemies and quickly send in light ground forces to mop up and take prisoners. When confronted with sufficiently heavy resistance, Collectors flee.
Seeker swarms are technological devices used by the Collectors. They have the appearance of large light-brown insects, deployed in swarms from Collector ships. Once released, the swarms seek organic targets and sting them, leaving their prey in a paralytic stasis-like state. This allows the Collectors to disable the populace of entire colonies, whereupon they move in and gather the bodies for transportation. In the aftermath of the Battle of the Citadel, the Collectors made full use of their seeker swarms on human colonies and began abducting their inhabitants. One such planet was Freedom's Progress, where all humans were taken, the sole survivor being a quarian, Veetor'Nara, who was on his Pilgrimage. Though mentally unbalanced by the encounter, Veetor had managed to record the actions of the seeker swarms, the recording being handed to Commander Shepard, who had begun working for Cerberus to stop the recent raids against Systems Alliance worlds. After an analysis of the video, the Illusive Man asked for Shepard to find Mordin Solus and use his scientific expertise to create a vaccine to repel the paralytic effects of the seeker swarms. Solus later managed to develop an experimental countermeasure that made wearers theoretically invisible to the swarms. The countermeasure was successfully tested when the Collectors attacked the human colony on Horizon. The countermeasure, however, was unable to provide protection against heavy concentrations of seekers, such as those later encountered by Shepard in the Collector base. It proved possible, however, to generate a biotic field that the swarms cannot penetrate.
The Seeker Swarm is a Collector unit encountered in Mass Effect 3. Collector Captains deploy Swarms to disable enemy abilities. Seeker Swarms move quickly towards a target. When they connect, their victims are unable to use any powers for an extended period of time. The explosion they create can also damage you. Seeker Swarms move fast and can be hard to target due to their shape. They only have a small amount of health, but it's much higher than their size would suggest.
The Seeker Plague is a Collector unit encountered in Mass Effect 3. It is an enhanced variant of the Seeker Swarm. Possessed Collector Captains deploy plagues to paralyze opponents. Once launched, a Seeker Plague targets players in order to explode near them. If a player is caught in the Plague, their powers will be disabled for a short length of time. Seeker Plagues are relatively weak enemies, but they do possess a barrier for added protection. Their speed and small size make them hard to hit and can allow them to sneak up on players.
Collector Drones are the common troopers of the Collector race. Drones are armed with the standard Collector Assault Rifle. Drones can have barriers at higher difficulty levels. Collector Drones should not be underestimated, as they are fairly accurate and can whittle down shields surprisingly fast if not in cover. This can be dangerous if other, more powerful Collector units are present, even more so on higher difficulties. Taking them out first should be considered as they are easier to kill and can, like any other unit, be possessed by Harbinger, making them very dangerous.
The Collector Trooper is a Collector unit added in Mass Effect 3's multiplayer with the Retaliation Pack DLC. Collector Troopers are equipped with Collector SMGs for ranged combat, but can use organic blades for melee. They can also throw Frag Grenades at their enemies, often to flush them out of cover. Collector Troopers have a moderate amount of health, and will frequently take cover. They can also perform combat rolls to avoid attacks. With their relatively weak health (if they become possessed, they gain a weak barrier), most tactics you use for a Cerberus Assault Trooper will work just as well for Collector Troopers. However, take caution when engaging Collector Troopers individually as they are usually accompanied by a Collector Captain or a much deadlier foe, such as a Scion or Praetorian. The Collector Trooper's weapon tracers are light grey, making them very hard to see. It's very possible to be taking fire from one without noticing, which can turn a casual hop from cover to cover into a very bad idea.
The Possessed Trooper is a Collector unit encountered in Mass Effect 3. It is an enhanced variant of the Collector Trooper. The Possessed Trooper is armed with a Collector SMG, the same as a Collector Trooper. The Possessed Trooper can deploy a Collector Web to snare enemies. It has moderate health and barriers, and can dodge roll to avoid attacks.
Collector Guardians are the elite Collector combatants. Guardians possess the Collector Assault Rifle, which they can arm with Warp Ammo. Their weapons utilize a burst-fire mode similar to M-15 Vindicators which can be devastating to your shields and biotic barriers on higher difficulties. Guardians have strong biotic barriers and can deploy anti-ballistic shields, similar to the geth hex shield in Mass Effect. Collector Guardians are the only Collectors capable of regenerating their barriers. As such, it is advisable to ensure that a Guardian is slain quickly once its barrier drops, not giving it a chance to replenish its defenses. Like all other Collector soldiers, Guardians can be possessed by Harbinger.
Collector Assassins are the long-range marksmen of the Collectors. Assassins are armed with the Collector Particle Beam, which has an extremely high rate of fire and will tear through shields and barriers with ease. Assassins have a light biotic barrier, which becomes stronger on higher difficulties. Collector Assassins are almost always in cover and far away, usually behind other Collector troops. They use their Collector Particle Beams as sniper rifles, firing them in long bursts to pulverize their enemy. When working in tandem with Harbinger, the Assassin is particularly deadly; its Particle Beam will keep you pinned down while Harbinger closes in, allowing him to hit you with his cover-breaking attack, thus opening you up to lethal Collector fire. As such, you may consider prioritizing Assassins, especially before Harbinger shows up. Counter-sniping, the Pull-Throw combo, and Incendiary Ammo are all useful for interrupting or killing the Assassin after its barrier has been stripped. Reave is particularly useful, possessing the ability to strip an Assassin's barrier as well as flush an unprotected Assassin out of cover or temporarily halt their fire with its stun effect. Warp is also good for detonating the biotic barrier, causing damage and potentially killing the assassin (if it has a low biotic barrier) and other Collectors. Like all Collector troops, Collector Assassins are susceptible to possession by Harbinger.
The Collector Captain is a Collector unit encountered in 2186. Collector Captains are armed with Collector Assault Rifles. They deploy Seeker Swarms. Collector Captains use biotic barriers for defense.
The Possessed Captain is a Collector unit encountered in 2186. It is an enhanced variant of the Collector Captain. Possessed Captains are armed with Collector Assault Rifles, and can release Seeker Plagues. Like their normal counterparts, Possessed Captains have biotic barriers.
While possessing the Collector General directly, Harbinger can also control an individual Collector soldier in combat. This soldier gains a substantial advantage in strength, as well as the use of biotic abilities. The soldier whose body is possessed by Harbinger starts to crack open showing magma-like appearances on the skin. When Harbinger possesses any Collector trooper in the fight, the Harbinger-Collector will become a full-health unit, with fully-charged barriers and armor, even if the host is near death. Harbinger will advance and attempt to engage Shepard at point-blank range. It possesses an extremely powerful and unknown biotic attack, which can penetrate thin cover, and cause Shepard to stagger back. The attack, when both spawned and generated when it hits cover or its target, resembles a biotic Singularity. Harbinger can also spawn biotic attacks similar to Warp that drain Shepard's shields and health significantly. The higher the difficulty setting, the more it will use these abilities. On Insanity difficulty, its biotic attacks can become a non-stop barrage. Harbinger also has a short-ranged splash attack which is similar to the Praetorian's Death Choir. It can deplete Shepard's shields in a single hit, if Insanity difficulty level is chosen. In addition, this deadly attack has an incinerating effect that will cause Shepard to stagger back, which could be a death sentence on higher difficulty levels. Harbinger possesses strong biotic barriers and armor. When fighting Harbinger, it is best to keep at a distance, since its ranged attack is slower than the average biotic/tech ability. Its shots are capable of stunning a character in one hit and can quickly bring down the average squad-mate in close quarters. It is also capable of possessing multiple Collectors in a single fight so it might be better to deal with the weaker minions first before focusing on the master, provided there is sufficient safe distance between Shepard and Harbinger-Collector.
The Collector General was a unique Collector who controlled the rest of the Collectors from the Collector base. Like all Collectors, the General was a victim of Harbinger's Mind Control up until its race's extinction at the hands of Shepard and the Commander's squad. The General's physical appearance was quite different from the standard Collector which has a humanoid shape. It had a more insectoid appearance, with a larger head, a short body, and multiple limbs, enabling it to operate numerous command interfaces. Its body strongly resembled the Praetorians deployed by the Collectors. The Collector General was a servant of the Reapers, specifically the one referred to as Harbinger, and was apparently directly controlled by Harbinger. The General could possess any normal Collector at any time, making them significantly more powerful and unlocking their biotic potential, making them a dangerous foe on the battlefield. This ability was taken advantage of by Harbinger while he possessed the General. The Collector General was always seen with glowing eyes, similar to what happened when he assumed control over an ordinary Collector.
The Collector Web is a Collector unit encountered in Mass Effect 3. Collector Webs have no offensive capabilities. Collector Webs have moderate barriers. When players walk into a Web, their movement speed will be drastically decreased, and they will be unable to attempt evasion manoeuvres.
A Collector Cruiser is a massive vessel capable of carrying large numbers of Collectors, Husks, Abominations, Scions, Praetorians and Seeker swarms along with enough stasis pods to capture every human colony in the Terminus Systems and still gather more from Earth. A Collector Cruiser is seen in Mass Effect 2, and is currently the only known Collector ship type. The ships are vast in size, easily dwarfing both the original Normandy and her larger successor. As is typical of Collector technology and design, the vessels are hybrids of organic protrusions with a metallic superstructure. The interiors consists of cave-like hallways, similar to an insect hive, and vast open areas traversed by floating hexagonal platforms. Despite its huge size these ships are capable of landing on the surface of a planet (resting vertically) although they require an enormous rocket engine to propel them back into space. The cruisers are armed with a large particle beam weapon which, while forward-firing by default, is capable of multi-directional fire. The weapon is capable of firing multiple shots in quick succession or a single devastating blast. Being a particle beam weapon, it ignores kinetic barriers, and it is also powerful and accurate enough to cripple an Alliance Navy frigate in only a few shots. They also appear to be equipped with sensors capable of detecting a vessel with a heat retaining stealth system (such as the Normandy). Details of this capability are never revealed. The Collector ships are equipped with an Identify Friend/Foe (IFF) system that allows them to traverse the Omega 4 Relay without harm. Despite being able to endure the atmospheric heat of reentry to land on planets, the Collector cruiser appears to be no more immune to sustained bombardment from Alliance anti-aircraft GARDIAN turrets than any other warship. This may just be a result of the laser based weaponry also ignoring kinetic barriers (for an example of another warship brought down by relatively small arms fire, see the destruction of the SSV Iwo Jima).