The origins of tattooing are very ancient, and the modern fascination with the practice serves to remind us that it has been an enduring fixture in human history. Its functions are many and often overlap, but the particular focus here is on the tattoo as an aspect of punishment. Comparative evidence, however, is welcomed whenever it proves useful. This article first marshals and examines the late antique literary evidence (which is predominantly Christian) extending from North Africa in the third century to Constantinople in the ninth. Then that evidence is put in its legal context. From at least the time of Augustus, the penal tattoo, which was generally placed on the face or forehead, had been associated with degradation. Such remained the case in late antiquity, and it also becomes clear that the tattoo accompanied a sentence of exile and hard labor, usually in mines or quarries. The deeper meaning of the tattoo and its placement on the forehead is considered in the light of modern understandings. There follows a discussion of the actual form taken by the tattoo, which normally displayed the name of the crime, the name of the emperor, or the name of the punishment. Based on the available data, the last option appears to have been the most common penal tattoo in this period. Finally, the article hypothesizes that the Christians effected a transformation of the tattoo and subverted its original intent, so that, rather than being a sign of punishment, it became a sign of glory in which one could take pride. Thus the penal function, in some settings at least, was overtaken by a primarily religious one.