Dr. Martin Brenner

Dr. Martin Brenner runs the Hawkins National Laboratory's shadowy research program, presenting himself to young Eleven as a father figure — the only one she calls 'Papa.' Calm, soft-spoken, and unfailingly gentle in manner, he oversees experiments on children with psychic abilities, framing his control as care and his tests as necessary.

Modine's performance is unsettling precisely because it withholds menace — he never raises his voice or looms as a monster should. That mildness is the writing's best trick: a scientist who speaks like a kind mentor while running something monstrous, so the horror comes from the gap between his tone and his purpose.