The Geth VI is a virtual intelligence created by the "true" geth to study the Reapers if Legion did not survive the suicide mission, was sold to Cerberus or was never activated. It is first encountered during the mission to disable a geth dreadnought. The Geth VI also accompanies Commander Shepard into the geth server and provides support during the assault on the Reaper base on Rannoch.
The Geth VI is, for the most part, physically identical to Legion. Non-standard elements of the Geth VI's armor, such as Shepard's N7 armor shoulder piece and the hole in the geth's torso, are recreated via hologram. Aboard the Normandy SR-2, it explains that it is also a unique mobile platform containing 1,183 geth programs, made for the similar purpose of studying the Reapers and communicating with organics.
A notable difference is the Geth VI's absence of data on events occurring after Saren Arterius' assault on Eden Prime. This lack of experience results in the geth consensus' skeptical views toward organic life. While Shepard insists on calling it Legion, it repeatedly affirms that it is not the same entity. The Geth VI is notably less friendly toward Shepard than Legion had been, and states that it cannot understand why Legion had befriended an organic such as Shepard. If Shepard dealt with the geth heretics, the Geth VI also cannot understand why Legion deferred the choice of the heretics' fate to an organic.
The Rannoch campaign can end in one of two ways if the Geth VI is present; the peaceful outcome is not possible. If Shepard chooses to let the geth die, the Geth VI will assault Shepard and claim "We were correct to distrust organics" and will attempt to upload the code before being attacked and killed by Tali, who claims that Legion would have understood. If Tali is not present, Shala'Raan will kill the geth with a shotgun. Meanwhile the quarians will emerge victorious over the geth fleet. If Shepard chooses to upload the Reaper code and save the geth, then Geth VI dissolves itself into the consensus to achieve true intelligence for all other geth after saying that their "skepticism was misplaced" and thanks Shepard. The upgraded geth then emerge victorious over the quarian fleet.
- If Shepard personally interacted with Legion in Mass Effect 2 (that is, if it was activated but did not survive the suicide mission), subtitles and mouse-over will still refer to the Geth VI as "Legion", despite its repeated claim that it is not Legion. Otherwise, it is called "Geth VI" in-game, and Shepard is unfamiliar with its design. This also happens in playthroughs not imported from Mass Effect 2, which assume Shepard never activated Legion.