The illusion of control is a cognitive bias that guides individuals to overestimate their personal ability to influence outcomes that are primarily determined by chance. This chapter illustrates the phenomenon through the life and surgical practice of Robert Liston, the “fastest knife in the West End,” who, in the pre-anesthetic era, achieved extraordinary fame for his skill, strength, and speed in performing amputations. Although his speed reduced the duration of patient suffering, Liston came to believe he could also diminish the intensity of pain, attributing to himself an impossible degree of control over everyone’s pain threshold. Using this case, the chapter reviews the psychological foundations of the illusion of control, from Ellen Langer’s classic experiments to contemporary models that explain how familiarity, active participation, prior successes, and goal clarity foster confusion between skill and chance. The influence of this bias is also explored in personal life, magical thinking, high-risk decision-making, and behaviors such as compulsive gambling. In the medical and surgical fields, examples such as overdiagnosis, overtreatment, overestimation of prognosis, and the adoption of surgical rituals are analyzed. Finally, strategies are proposed to mitigate the bias through realistic assessments of control, reflective thinking, group decision-making, and rigorous application of the scientific method.