In aesthetics, the uncanny valley (Japanese: 不気味の谷, Hepburn: bukimi no tani) is a hypothesized relation between an object's degree of resemblance to a human being and the emotional response to the object. The concept suggests that humanoid objects that imperfectly resemble actual human beings provoke uncanny or strangely familiar feelings of uneasiness and revulsion in observers. "Valley" denotes a dip in the human observer's affinity for the replica—a relation that otherwise increases with the replica's human likeness.

Examples of the phenomenon exist among robotics, 3D computer animations and lifelike dolls. The rising prevalence of technologies e.g., virtual reality, augmented reality, and photorealistic computer animation has propagated discussions and citations of the "valley"; such conversation has enhanced the construct's verisimilitude. The uncanny valley hypothesis predicts that an entity appearing almost human will risk eliciting cold, eerie feelings in viewers.