mass effect reaper image - FIN7

The Reapers, known by the geth as the Old Machines, are a highly advanced machine race of synthetic-organic starships. The Reapers reside in dark space, the vast, mostly starless space between galaxies. They hibernate there, dormant for fifty thousand years at a time, 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, 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 was of little concern to its kind.
Sovereign also reveals that the Reapers were the original creators of the Citadel and the mass relay network. These massive constructs 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 sentient life in a repeating cycle of purges that has continued relentlessly over countless millennia.