Legion

"Organics do not choose to fear us, It is a function of your hardware."

Legion is a geth that has learned to think on its own, separate from the neural network. It marks a "natural evolution" of the geth, who are normally tied to groups in order to maintain sentience, having developed the ability to operate independently and even speak. It bears a gaping hole in its right chest cavity.

Legion is obsessed with Commander Shepard, even going so far as to have a piece of Shepard's discarded armor incorporated into its own. Shepard must eventually confront Legion to find out why it is hunting Shepard.

Trivia

 * Legion may be named after the biblical demon Legion, in reference to the quote "My name is Legion: for we are many.", as the geth possess a unifying neural network. A similar phrase is uttered by Sovereign during its encounter with Shepard in Mass Effect.