The branding of slaves in Antiquity represents one of the darkest, yet most fundamental, pages in the history of body modification. For a modern person, a tattoo is an act of self-expression, an aesthetic choice, or a tribute to art. However, in the Ancient world, especially in Greece and Rome, permanent marks on the skin (known as stigma or stigmata) most often served as a legal instrument denoting status, crime, or, most critically, ownership. As professional tattoo encyclopedists, we are obliged to study this phenomenon not only from a historical but also a cultural perspective to understand how the concept of an owner’s mark influenced the perception of tattooing throughout millennia. This is not just a history of punishment; it is a deep analysis of how the skin was used as a legal document and how it defined a person’s social status without the right to voice.