In Eastern Christian Orthodox iconography, Saint Christopher sometimes appears with the head of a dog. As a consummate outsider who would become the patron saint of travellers, Christopher came to be associated with tales of far-flung peoples who blurred the boundary between human and animal—and the connection came to be taken literally. The representation was not isolated to the East; in the medieval Irish Passion of St. Christopher, “This Christopher was one of the Dog-heads, a race that had the heads of dogs and ate human flesh” (source). Even the more traditional Western narrative maintains this sense of otherness by depicting Christopher as a fearsome giant. The story of his conversion to Christianity and sainthood is thus a narrative about the possibility of salvation for even those at the margins of humanity.
This image is from Cappadocia, now in Turkey, and dates from the 17th century. (source)