Edmund Kemper

Kemper is already behind bars when Holden Ford comes to interview him, a soft-spoken, immensely tall inmate who turns out to be startlingly articulate about his own psychology. He is polite, curious about the FBI's research, and eager to talk — almost too eager, filling silences with an intelligence that unsettles everyone around him.

Cameron Britton plays him with an unnerving gentleness, all patient eye contact and measured cadence, so the horror sits underneath ordinary conversation rather than in any obvious menace. The writing lets him be genuinely insightful about the men investigating him, which is what makes the scenes so uncomfortable — he's frequently the smartest, most self-aware person in the room.