Philip Zimbardo is an American psychologist and a professor emeritus at Stanford University. He rose to prominence for his Stanford Prison Experiment (SPE) and has authored numerous books, including The Time Paradox, and The Time Cure. He is the founder and president of the Heroic Imagination Project. Zimbardo also served as an expert psychological witness for the trials of United States soldiers related to the Abu Ghraib prison torture and prisoner abuse. He is married to the prominent social psychologist Christina Maslach.

Prisoner Doug-8612 is the first prisoner arrested for the Stanford Prison Experiment and the first person Zimbardo is forced to release from the experiment due to a mental breakdown. Initially rebellious, Doug quickly loses his grip on reality and demands release. He comes to believe Zimbardo will not release the prisoners in the experiment, and his condition worsens, necessitating his early release.

Guard Hellman is the most brutal, authoritarian, and sadistic guard in the Stanford Prison Experiment. Over the several days of the experiment, he progresses the psychological and physical torture of the prisoners, eventually forcing them to engage in homoerotic acts that could accurately be described as sexual assault. He later states that during the Stanford Prison Experiment, he was performing experiments of his own, to determine how far he could push the prisoners before they pushed back.