As early as the sixth century there have appeared certain images of Jesus that were said to be acheiropoietoi--Greek for "not made with hands." There were different versions of these and as many legends to explain their allegedly miraculous origin. Some modern writers have placed the Shroud of Turin in this genre.
Perhaps the earliest "not made with hands" legend concerns the "Image of Edessa." A mid-fourth-century Syriac manuscript known as The Doctrine of Addai, tells how King of Abgar of Edessa (now Urja, in southcentral Turkey) wrote a letter to Jesus asking him to come and cure him of leprosy. Jesus was unable to visit Abgar, but sent a miraculous self-portrait as a "consolation" for his disease. A tenth-century version of the tale has the magical cloth imbued with curative power.
From the Middle Ages were supposedly miraculous portraits of Jesus that came to be known as "Veronicas." Supposedly, Veronica was a woman from Jerusalem who was so moved by pity at witnessing Jesus struggling with his cross toward Golgotha that she wiped his face with her veil (or kercheif). In some versions of the tale she offered the cloth to Jesus for him to wipe his face. In return, he caused his visage to be miraculously imprinted thereon.
Scholars believe that "veronica" is a corruption of vera iconica, medieval Latin for "true image." It seems likely that the name Veronica then prompted the pious legend to explain how Jesus's face appeared on the cloth.
Although the "veronicas" were supposedly miraculous, they were in fact painted. To explain how there could be so many of the "original," another legend was created to explain that the image could duplicate itself miraculously. (See Joe Nickell, Looking for a Miracle, Amherst, N.Y.: Prometheus Books, 1998, pp. 19-22.)
Some equate the Shroud of Turin with the earlier Edessan Image, even though the "shroud" bears not just a facial image but the entire front and back impressions of an apparently crucified man. In his the Shroud of Turin (Garden City, N.Y.: Image Books, 1979, pp. 97-124.) Ian Wilson suggests that the shroud could have been folded so that only the face showed, thus disguising the shroud as a portrait for centuries.
This notion lacks supporting evidence, and in any case the Shroud of Turin has been shown to be the work of a fourteenth-century artist. According to a later bishop's report to Pope Clement VII, the artist confessed it was his handiwork. Moreover, modern scientific tests revealed the image was rendered in tempera paint, and radiocarbon dating showed that the cloth was from the time of the forger's confession. (See Joe Nickell, Inquest on the Shroud of Turin, Amherst, N.Y.: Prometheus Books, 1998.)
A supposedly related "relic" is the Cloth of Oviedo. Located in the Cathedral of Oviedo in northern Spain, this is purported to be the sudarium--or "napkin"--that covered Jesus's face in the tomb. But just as there were numerous "true" shrouds (at least forty-three in Europe alone), there were many reputedly genuine sudaria. Despite pseudoscientific attempts to link the Oviedo Clothwith the Shroud of Turin, the alleged sudarium lacks any facial image. Had this cloth indeed covered the face of Jesus, it would have blocked the facial image from imprinting on the "shroud." Like many of the claims regarding the Turin cloth, those concerning the Oviedo cloth are characterized by pseudoscience and possibly worse. (For a discussion see Joe Nickell, "The Sacred Cloth of Oviedo," Skeptical Briefs, September 2001, pp. 10-11.)
In addition to the "not made with hands" images of Jesus, there is also a famous, allegedly miraculous self-portrait of the Virgin Mary. Known as the Image of Guadalupe, it is a sixteenth-century depiction of Jesus's mother that she reputedly caused to be imprinted on the Aztec convert's cloak. Enshrined in church in Mexico City, the cloth has been shown to be a native artist's paintin, the tale apocryphal, and the convert probably fictitious. Nevertheless, "Juan Diego" was canonized a saint of the Catholic Church.
(See Joe Nickell, "'Miraculous' Image of Guadalupe, Skeptical Inquirer, September/October 2002, p 13.)