A cephalophore (from the Greek for "head-carrier") is a saint who is generally depicted carrying his or her own head. In Christian art, this was usually meant to signify that the subject in question had been martyred by beheading. Handling the halo in this circumstance offers a unique challenge for the artist, some put the halo where the head used to be, others have the saint carrying the halo along with the head, and some split the difference.
The term "cephalophore" was first used in a French article by Marcel Hébert, "Les martyrs céphalophores Euchaire, Elophe et Libaire", in Revue de l'Université de Bruxelles, v. 19 (1914).
The topos can be traced to two sources. In a homily on Saints Juventinus and Maximinus, John Chrysostom asserted that the severed head of a martyr was more terrifying to the devil than when it was able to speak. "He then compared soldiers showing their wounds received in battle to martyrs holding their severed head in their hands and presenting it to Christ". The other source was the Western vita of Saint Denis, founder of the see of Paris, who was identified in the text with Dionysius the Areopagite.
Thus, an original, and perhaps the most famous cephalophore is Denis, patron saint of Paris, who, according to the Golden Legend, miraculously preached with his head in his hands while journeying the seven miles from Montmartre to his burying place. Although St Denis is the best known of the saintly head-carriers, there were many others; the folklorist Émile Nourry counted no less than 134 examples of cephalophory in French hagiographic literature alone. Given the frequency with which relics were stolen in medieval Europe, stories like this, in which a saint clearly indicates his or her chosen burial site, may have developed as a way of discouraging such acts of furta sacra.