In George Orwell's dystopian novel 1984, thoughtcrime is the criminal act of holding unspoken beliefs or doubts that oppose or question the ruling party of Oceania. In the book, the government attempts to control not only the speech and actions, but also the thoughts of its subjects.

Entertaining those unacceptable thoughts is referred to as crimethink, and facecrime was an indication that a person is guilty of thoughtcrime based on facial expression.

Orwell's Thought Police are charged with uncovering and punishing thoughtcrime and thought-criminals. They use psychological methods and omnipresent surveillance to search, find, monitor, and arrest members of society who could challenge authority and the status quo – even if only by thought.