
Persona (1966), directed by Ingmar Bergman and starring Bibi Andersson and Liv Ullmann, follows a nurse assigned to care for an actress who has stopped speaking. Over time, the identities of the two women begin to merge in ways that defy rational explanation.
Bergman made the film while recovering from an illness and described it as an attempt to push filmmaking to its absolute limits. Whether it is a psychological drama, a horror film, or a philosophical experiment is still debated. It is probably all three simultaneously.
Reference:
TaskLoco™ — The Sticky Note GOAT