|Voiced by:||David Faustino|
Sean Miller was a troubled kid.
Sean Miller was a student at Hamilton Hill High School, where he shared a history class with Terry McGinnis and Max Gibson. Sean was a typical delinquent who seemed to find pleasure in his vile actions as well as a disregard for human life. After a joyride in a cargo truck, his parents sent him to Dr. Wheeler's clinic.
Shortly after, he welcomed Chelsea Cunningham into the clinic, and served as her guide in the clinic. Through this he also reveals a severe paranoid side to himself, accusing her (and others, such as Terry) of talking about him behind his back. When Terry came to "visit", Sean picked a fight with him. Unfortunately, Vincent broke them up and Dr. Wheeler sent him to ISO. The next morning, as Sean and Terry were transported to the ISO rooms, they started a revolt. Sean freed as many of the other kids as he could, but they were overrun by guards.
Sean snuck away from the fight and made it to Dr. Wheeler's office. He threatened to kill him by throwing him off the roof. Batman persuaded him to let Wheeler go. Sean was arrested by guards, but Wheeler was arrested too and the clinic was shut down. For his attempted murder, Sean was arrested too.