Joaquín María Argamasilla de la Cerda y Elío (4 April 1905 – 27 May 1987) was a Spanish noble who was the 11th Marquess de Santacara, but he is better known for claiming in the early 1920s a supposed ability to see through opaque objects. Argamasilla convinced important people of the era such as Gustav Geley and Charles Richet of his powers,^[1] but he was exposed by Harry Houdini as a fraud in 1924.^[2]

Joaquín Argamasilla was encouraged in his parapsychology career by his father, the Marquis de Santa Cara, who was convinced that his son had psychic powers. Argamasilla was promoted as having X-ray vision that could penetrate metal.^[3]: 132 For example, he was seemingly able to read the time on a watch through a case.^[3]: 132 Among the audience of these shows was the Spanish writer Valle-Inclan, who was a friend of the father of the psychic and became convinced that Joaquín's powers were real.^[4]

Argamasilla's fame led him in 1924 to the Pennsylvania Hotel in New York City. There he met magician Harry Houdini, who became convinced that he was a fraud who just peeked through his simple blindfold and lifted up the edge of the box so he could look inside it without others noticing.^[3]: 134 Argamasilla could not replicate his abilities when forced to do the same with a box not owned by him.^[5] Houdini regarded Argamasilla to be "a very clever manipulator" who "acts his part in such as manner as to insure misdirection".^[3]: 135

Argamasilla never did another psychic demonstration. He later was assigned the position of general director of Film and Theatre (1952-1955).^[6]

Argamasilla died on 27 May 1987 in Bilbao, Spain at the age of 82.^[7]

A fictional version of Argamasilla (in which his powers turn out to be real) appears in the 14th episode of the Spanish science-fiction series El Ministerio del Tiempo.^[8]