Reaper (Mass Effect)

The Reapers, known by the Geth as the Old Machines, are a highly advanced machine race of synthetic/organic starships from the Mass Effect Universe. The Reapers reside in dark space, the empty, starless space between galaxies. They hibernate there, dormant for thousands of years, before they are given the signal to return. Their origins are completely unknown. The first Reaper known to have communicated with organic life, referred to by Saren Arterius as Sovereign and by the Geth as Nazara, claimed that the Reapers have neither beginning nor end. Even their true name is a mystery; "Reapers" was a name bestowed by the Protheans, and Sovereign stated that whatever the Protheans chose to call them is irrelevant: "we simply... are."

Sovereign also reveals that the Reapers were the original creators of the Citadel and the mass relay network. Smaller pieces of their technology also exist throughout the galaxy. The mass relays exist so that any intelligent life in the galaxy would eventually discover them and base their technology upon them – all part of a scheme to harvest the galaxy’s sapient life in a repeating cycle of purges that has continued relentlessly over countless millions of years.

Design
Capital ship Reapers bear a superficial resemblance to a Reaper cuttlefish, with a two-kilometre long, bulky and semi-cylindrical body, a tapering plate over the rear and a mass of metallic "tentacles" extending from its front end, in addition to six jointed legs extending from its body. When the Reaper fleet is revealed in dark space they are all shown with this basic design (however, one Reaper in the foreground shown when Harbinger awakens the fleet seems to resemble a scarab beetle) but with great diversity in tentacle number, shape and orientation, some with extended heads and others (particularly Harbinger) having multiple glowing eyes. This diversity is presumably due to the Reapers' reproduction method, in which vast numbers of a single species are harvested, melted down into a raw genetic paste, and then used to construct a "larva" that takes on the characteristics of the species from which it was created. The core of the Reaper is in the image of the species that was used to create it while the exterior follows a similar design that is most efficient for their purpose.

There seem to be a few 'classes' of Reaper, such as the capital ships (of which Sovereign was one), and the destroyers, which have legs and move across the ground. These have a beetle-like head and their main weapon is located just above this. These are only around 160m tall, but still formidable opponents.

Sovereign's design appears to have influenced the 'heretic' geth. This is not surprising, as these geth worship the Reapers as "gods", considering them to be the epitome of independent AI. Wherever the heretic geth become entrenched they build monuments to the Reapers resembling Sovereign's 'tentacles' around a glowing orb, and genuflect. Sovereign was apparently insulted by the adoration of such simple, base synthetics, but it did see their value as pawns and possible replacements for the flawed and organic keepers.

Technology
Even without their indoctrinating influence, Reapers are immensely powerful warships and their technology is devastating. Sovereign’s destructive power was unrivaled in the known galaxy. Each of the "tentacles" extending from its bow was equipped with a powerful "magnetohydrodynamic" weapon which ejects a stream of molten metal at a fraction of the speed of light which could tear through a cruiser in a single sustained burst. Its gigantic spinal-mounted gun was able to rip through the hulls of even the largest of dreadnought-class ships with ease, effortlessly penetrating their kinetic barriers. Sovereign's defences included powerful shields that could block the projectiles of an entire fleet, along with an incredibly strong hull. Though they are sentient machines, the Reapers have habitable interiors that can transport a crew, either to help spread their indoctrinated slaves or to allow these slaves to tend to them, probably both. Speculation in the Codex suggests that each individual Reaper has a massive element zero core (proven on the Derelict Reaper) which, coupled with the likely enormous quantities of energies at its disposal, allows it to generate the staggering mass effect field needed to land on a planet.

However, the Reapers are not invincible. When the Reapers go into states of hibernation between cycles, they are vulnerable. By taking refuge in dark space, the Reapers ensure they will not be discovered by accident and destroyed while they wait for their vanguard to open the Citadel mass relay. A concentrated effort by the fleets of organic races could also destroy a Reaper even if it is at full power: a single fleet managed to destroy Sovereign when its shields and weapons were disabled.

Aside from their formidable firepower and indoctrination, Reapers are also capable of mustering up their own ground forces to attack their enemies: Husks. Husks are aggressive, mindless drones, created from organic beings who are exposed to Reaper technology, such as Dragon's teeth, resulting in their organic bodies being consumed by cybernetics. Husks are used as shock troops and swarm enemies in waves. Husks can be modified and combined to create Abominations, Scions, and Praetorians.

History
The Reapers have been around for millions of years- the derelict Reaper discovered by Commander Shepard was 37 million years old.

The cycle of extinction has been going on for as long if not longer, ever since the Reaper's creators were destroyed by them. They laid a trap for the races of the galaxy in the form of the mass relays, which offered instant transport around the galaxy (leading to the impressive Citadel), almost certainly better than the FTL technology the discoverers would possess. This channelled the development of the race's technology, possibly so that it was more likely to be usable by the Reapers when they returned. This path also made element zero-based weapons and armour technology more probable.

The Reapers created or enslaved the Keepers as guardians of the Citadel, and programmed them to maintain the Citadel while also preventing the residents from learning its secrets. When the vanguard left by the Reapers in the galaxy broadcasted a signal, the Keepers would activate the station's mass relay, bringing in the Reapers from dark space. As the Citadel would be the centre of galactic finance, information and society, the Reapers controlling it would allow them to find all worlds and settlements of the species there. They will also have control of the relay network from here.

After harvesting the galaxy, they remove all traces of their presence and go back to dark space.