Mysterious Figure

The  Mysterious Figure  is an individual who hires a mercenary group to assassinate Commander Shepard whilst the Normandy crew is docked on the Citadel for shore leave in 2186. This person takes a particular interest in stealing Shepard's identity, and hides behind voice and visual disguisers to protect theirs.

History
The Mysterious Figure eventually reveals itself to be a clone originally created by Cerberus to provide spare organs and limbs for the real Commander Shepard, who was being revived by the Lazarus Project.

At some point in its development it was stored in the Minuteman Station, skinless and under life support. Once Cerberus obtained Shepard's Spectre dossier the Illusive Man deprioritized the clone project and allowed project overseer Miranda Lawson to continue using it for testing.

Sometime in 2184, the order was given for the clone's termination. Agent Rasa had other ideas and decided to liberate it from Cerberus hands. A violent shootout at Lazarus Research Station resulted in Rasa severing ties with Cerberus and escaping with the clone's tank. One of its known hiding places was Rasa's old stomping grounds on an asteroid orbiting Themis.

The clone remained in storage until six months before the Reaper invasion in 2186, when it was awoken by Rasa (then known as Maya Brooks). Over the intervening months during Shepard's incarceration, the clone learned "how to be human" with the help of neural implants, and with Brooks' help devised a plan to kill and assume the role of the Commander in order to carry out a pro-human agenda. To accomplish this, the clone hired the CAT6 private military corporation to eliminate Shepard and his/her close allies, since the clone lacked the original's memories, thereby unable to perfectly impersonate the Commander.