A psychic is a person who claims to have a form of extra-sensory perception and can exhibit or feign abilities such as mind reading or precognition.
The origin and nature of these skills is unknown and varies with the individual. In popular culture, as demonstrated by agent Mudler and Scully among others, people tend to be skeptical of psychics as they are considered to be scammers. This leads then authentic psychics to hide or repress their faculty, or to be afraid of them. Generally perceptions and sensations need to be triggered by a particular feeling, traumatic event or an object to handle to establish a kind of intercession with the subtle planes of existence.
Some psychics are able to communicate with the spirits of the dead and receive from them information on the living, as demonstrated by Luther Lee Boggs who knew details of the relationship of the agent Scully with her recently deceased father. (TXF: "Beyond the Sea")
Other psychics instead have the power to read minds and use it to their own advantage, as The Stupendous Yappi, that made its power a source of financial gain. (TXF:"Clyde Bruckman's Final Repose", "José Chung's From Outer Space")
Mediums and psychics are also sometimes used by law enforcement to solve crimes, or are involved in them and are considered no less than meddlesome by police. It is the case of Sharon Pearl, who has had to cooperate with the resolution of a case. ("Invocation") Both Sharon Pearl and Clyde Bruckman are able to sense the energy and Bruckman was even able to predict the future, particularly the death of people nearby (TXF:"Clyde Bruckman's Final Repose")
Sometimes these visions are the result of witchcraft and may lead to madness, as happened to Melissa Turner, believed to be a witch descendant of the well-known witches of Salem, who foresaw the exact dead before the cursed doll unleash its attacks. (TXF: Chinga)