The "Mastermind" on Big Brother Season 27 (2025) is a mysterious figure who initiates a murder mystery hotel theme in the game. This Mastermind kidnaps host Julie Chen Moonves and steals the "HOH Relic." The HouseGuests are split into groups facing various challenges to solve puzzles and find clues to progress in the game. The Mastermind also secretly has an Accomplice among the houseguests. The identity of the Mastermind was not directly revealed in the available sources, but the Accomplice was revealed to be Amy Bingham. The game involves strategic twists and betrayals tied to the Mastermind's actions.
There are no clear public spoilers identifying the Mastermind's personal identity beyond the character's role in the game narrative. Discussions and theories among fans speculate about certain players, but no definitive reveal has been made in the mainstream media sources accessible.
Thus, the Mastermind is a game persona orchestrating the season's twists rather than a confirmed named contestant identity publicly disclosed as of September 27, 2025.