MKUltra was an illegal human experimentation program designed and undertaken by the U.S. Central Intelligence Agency (CIA) to develop procedures and identify drugs that could be used during interrogations to weaken individuals and force confessions through brainwashing and psychological torture. The term MKUltra is a CIA cryptonym: "MK" is an arbitrary prefix standing for the Office of Technical Service and "Ultra" is an arbitrary word out of a dictionary used to name this project. The program has been widely condemned as a violation of individual rights and an example of the CIA's abuse of power, with critics highlighting its disregard for consent and its corrosive impact on democratic principles.

Project MKUltra began in 1953 and was halted in 1973. MKUltra used numerous methods to manipulate its subjects' mental states and brain functions, such as the covert administration of high doses of psychoactive drugs (especially LSD) and other chemicals without the subjects' consent. Additionally, other methods beyond chemical compounds were used, including electroshocks, hypnosis, sensory deprivation, isolation, verbal and sexual abuse, and other forms of torture.