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.

Background
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. The clone was never utilized, however, and remained in storage until six months before the Reaper invasion in 2186, when it was awoken by ex-Cerberus agent 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.

Mass Effect 3: Citadel
Shortly after Cerberus' attempted coup on the Citadel, the clone implements its plan while Commander Shepard is ordered to go on shore leave. It purchases arms for its CAT6 troops via arms dealer Elijah Khan, hacks databases to steal Shepard's classified files, and sets a trap at a popular sushi restaurant in the Silversun Strip with the intent of obtaining the Commander's Spectre code.

The clone successfully obtains the Spectre code, but the original manages to escape being killed. To compensate, it uses Brooks to tie up loose ends by having Khan executed then luring Shepard and friends into another trap at the Citadel Archives by intentionally using the Spectre code to get itself and its mercenaries in.

Pretending to hold Brooks hostage during a clash between its troops and Shepard's team, the clone finally reveals itself and shares part of its life story and motivations. It puts up a signal blocker to intercept any transmissions, and manages to obtain the Normandy SR-2's command codes in the process. Impersonating the real Shepard and comming Samantha Traynor to get the Normandy prepped for emergency launch, the clone orders its mercs to execute Shepard and friends and moves forth deeper into the Archives.

Shepard and team thwart the kill order, but the clone's plan to have them all sealed within the Archives' iridium vaults ultimately becomes successful. Before trapping Shepard and their squad in one of the vaults, the clone and Brooks now reveal the full extent of their plan. The clone makes a show of pointing out that handprints can't be cloned, and promptly updates the Commander's records with the clone's own biometrics before setting out to be captain of the Normandy.

The trap doesn't last for long, and Shepard and friends soon resume the chase. The clone, meanwhile, has been busy taking over the ship: it fires Traynor for "fraternization"/"conduct unbecoming", and disposes of Shepard's cabin accessories in a big bin. Upon learning that the real Shepard has successfully boarded the ship, it leaves instructions for its troops to slow the Commander down, and on Brooks' suggestion heads down the armory to prepare for the showdown.

Shepard and the clone, now clad in N7 Armor, fight in the shuttle bay and eventually Shepard tackles the clone, causing them to tumble down the open boarding ramp and nearly fall off the edge. As Shepard's squadmates help the Commander up, the clone looks up to Brooks and watches her turn her back. The Commander is then faced with either helping the clone or kicking it off the ship to its death. If Shepard attempts the former, the clone will refuse the original's aid and purposely fall to its death, spitefully asking what it can live for before letting go.

While the clone is an exact physical replica of Commander Shepard, it only has the most superficial idea of what kind of person Commander Shepard is. For example, the clone is intensely xenophobic while the majority of Shepard's closest allies and potential love interests are aliens. Nor does the clone show any concern for the lives under its command (the CAT6 mercenaries), even considering them "cannon fodder", unlike Commander Shepard's fierce loyalty to the Normandy crew. The Clone describes itself as the lone wolf Shepard was supposed to be.

Capabilities
Offensive

The clone will have different powers, dependent on what class the player is using. The weapon it uses will also depend on the player's class. The clone will also attempt to mimic Shepard's close-quarters combat styles if close enough, excepting the Vanguard as it employs Nova instead.

The clone's weapons and powers are as follows:
 * Soldier - N7 Valkyrie, Fortification, Frag Grenade, Concussive Shot, Carnage
 * Infiltrator - Black Widow, Tactical Cloak, Incinerate
 * Engineer - N7 Hurricane, Combat Drone, Defense Drone, Incinerate
 * Adept - N7 Hurricane, Barrier, Warp
 * Vanguard - M-11 Wraith, Barrier, Charge, Nova, Warp
 * Sentinel - M-11 Wraith, Tech Armor, Warp, Incinerate

Defensive

The clone has moderate armor and shields, and also has access to five stacks of Medi-gel which will bring him/her back to full health when one is used.

Tactics

 * The clone fights aggressively according to whatever the player's class is, using powers and weaponry appropriate to that class.
 * An Infiltrator clone will not appear on your targeting display while it is cloaked, but as with all cloaked enemies it can be flushed out with weapons fire or by targeting an ability in its approximate location.
 * A Sentinel clone will only use its Tech Armor when the Normandy's bay doors are opened, and will never try to detonate it.
 * A Vanguard clone frequently spams Biotic Charge to close the distance on you, then Nova if you're near each other. Unlike your Nova, the clone's shields don't get depleted.
 * The clone will use medi-gel to fully recover its shields and armor whenever its armor is reduced below about half. Fortunately, the clone has only a finite supply, and will not take advantage of the shuttle bay's unlimited medi-gel crates.
 * Each version of the clone has tracking projectile attack that will momentarily stun you on contact, leaving you vulnerable, and cause damage over time. Be ready to take cover when the projectile is launched.
 * The clone is immune to quite a few powers, including Stasis and physics-based biotic attacks. Fortunately it is vulnerable to Energy Drain, and anti-armor abilities such as Warp work extremely well when you get its shields down.
 * The clone has a moderately tough shield/barrier, so it's best to wait until you can hit it with lots of concentrated damage all at once, punching through to the armor. If Brooks goes down, the clone may occasionally kneel down to revive her, presenting you with an opportunity to hit both at the same time.