Note: This page is about the incarnation of Cobra Commander from the 2009 movie and 2013 sequel. The mainstream version can be found here: Cobra Commander. Evil-doer Rex Lewis, known as the Doctor and Cobra Commander, is the primary antagonist of the G.I. Joe film series, serving as the true main antagonist in the 2009 movie G.I. Joe: Rise of Cobra and the active primary antagonist of the 2013 sequel G.I. Joe: Retaliation. He was a former soldier who became influenced by the Nanomite research from MARS Industries, his thirst for knowledge gave him little regard for human life and he eventually become the leader of a terrorist organization called Cobra. He was a close friend of Duke and brother to Ana Lewis, who later became the Baroness.