Shadow people are supernatural shadow-like humanoid figures that, according to believers, are seen flickering on walls and ceilings in the viewer’s peripheral vision. They are often reported moving with quick, jerky movements, and quickly disintegrate into walls or mirrors. They are believed to be evil and aggressive in nature, although a few people consider them to be a form of guardian angel.

In 2010, the apparitions were described as one of the most regularly reported paranormal phenomena in the United States. This is attributed to occasional reports on the Coast to Coast AM show, where paranormal researcher Heidi Hollis has been interviewed several times on the subject of shadow people. Hollis believes that shadow people have always existed, that they feed upon emotions of fear, and that they can be repelled by thinking positively. Others believe that shadow people may be the extra-dimensional inhabitants of another universe.

The stories of shadow people have been compared to those of the Raven Mocker, a witch from Cherokee Indian mythology who sometimes appears as a shadowy phantom, and the Islamic Jinn.

Several scientific principles can be used to explain reports of apparitional experiences such as shadow people. These include optical illusions or hallucinations brought on by physiological or psychological circumstances, drug use or side effects of medication, and the interaction of external agents on the human body. Another reason that could be behind the illusion is sleep deprivation, which may lead to hallucinations.