The Flash S01E18 Twin Streaks

Barry is cloned by Dr. Jason Brassel, who names the clone "Pollux", who Brassel designs a blue variant suit for. Upon learning that he is a clone and not a real person, Pollux goes on a rampage. He comes into conflict with the Flash, who is currently suffering symptoms of stress and fatigue. Brassel attempts to kill Barry after Pollux throws a bullet into him, but Pollux takes the bullet and dies in Barry's arms. Brassel succumbs from the injuries Pollux had earlier inflicted on him.