Catalepsy (from Ancient Greek katálēpsis, κατάληψις, "seizing, grasping") is a neurological condition characterized by muscular rigidity and fixity of posture regardless of external stimuli, as well as decreased sensitivity to pain.

[7] Suggested or induced rigid catalepsy, of extended limbs or even the entire body, sometimes tested with heavy weights, has been a staple of stage hypnosis shows and even academic demonstrations of hypnotism since the late 18th century, as proof of extraordinary physical abilities possible in trance states.

Armand D'Angour suggests that reports (such as that recounted in Plato's Symposium) of Socrates, in about 429 BC, standing perfectly still for hours on end during the Athenian campaign against Potidaea while seemingly deep in thought, are "too extreme to be considered wholly a matter of rational choice," and that "it is reasonable to suppose that it was the symptom of an underlying physiological or psychological condition", such as catalepsy.

Friar Laurence...Take thou this vial, being then in bed, And this distilléd liquor drink thou off; When presently through all thy veins shall run A cold and drowsy humour, for no pulse Shall keep his native progress, but surcease: No warmth, no breath, shall testify thou livest; The roses in thy lips and cheeks shall fade To paly ashes, thy eyes' windows fall, Like death, when he shuts up the day of life; Each part, deprived of supple government, Shall, stiff and stark and cold, appear like death: And in this borrow'd likeness of shrunk death Thou shalt continue two and forty hours, And then awake as from a pleasant sleep ... (Account of character Jem Rodney, the molecatcher)... coming up to him he saw that Marner's eyes were set like a dead man's, and he spoke to him and shook him, and his limbs were stiff, and his hands clutched the bag as if they'd been made of iron.

But there might be such a thing as a man's soul being loose from his body, and going out and in, like a bird out of its nest and back; and that was how folks got over-wise, for they went to school in this shell-less state to those who could teach them more than their neighbours could learn with their five senses and the parson.

(Narrator)... a peculiar interest had been centred in him ever since he had fallen at a prayer meeting into a mysterious rigidity and suspension of consciousness which, lasting for an hour or more, had been mistaken for death.

In Eugène Sue's The Mysteries of Paris, the villain Jacques Ferrand experiences a fit described as cataleptic in his final confrontation with Rodolphe, blinded by lamplight and hallucinating with visions of his fantasized Cecily.

In Arthur Conan Doyle's "The Adventure of the Resident Patient", a man feigns catalepsy to gain access to a neurologist's rooms; the doctor attempts to treat him with amyl nitrite.

In Poppy Z. Brite's Exquisite Corpse, the main character—Compton, a serial killer facing a lifetime sentence—uses shamanistic techniques to induce catalepsy and, convincingly appearing deceased, is able to escape prison.

In Sheridan Le Fanu's novella The Room in the Dragon Volant, a naïve young man falls foul of a criminal gang who employ a curious, bulbocapnine-like drug which induces catalepsy, as a result of which he narrowly escapes premature burial.