People experiencing alien control report that their thoughts, movements, actions, and emotions have been replaced by those of an "other." The latter is commonly a perceived persecutor of the patient. Here I describe the clinical phenomenology of alien control, mechanistic models that have been used to explain it, problems inherent in these models, the brain deficits and functional abnormalities associated with this symptom, and the means by which disordered agency may be examined in this perplexing condition. Our current state of knowledge implicates potentially reversible dysfunction in certain key brain regions (especially the right parietal cortex), which is temporally related to the presence of symptoms. Alien control is quintessentially a disorder of agency.