SCP-166 is a female of European descent with hoofed features such as branchial antlers, hoofed feet, and a short reindeer-like tail. She is currently in her late teens.

She was identified by a visitor at the Convent of Our Lady of Mercy in Galway, Ireland, where she had lived since infancy, and was subsequently transferred from the convent to the SCP Foundation.

Within a 15-meter radius of SCP-166, artifacts gradually revert to their raw state, with more complex items such as electronics and automobiles being affected more rapidly. Clothing and other items to be worn are also decomposed to a near-naked state, and organic cotton clothing is provided every month.

Currently, SCP-166 is back at the Convent of Our Lady of Mercy, protected from harm and living a peaceful life as a Catholic.

SCP-166 is not a succubus.

Initially, the SCP Foundation recorded SCP-166 as a succubus, but as research progressed, misinformation was removed and she is now treated as a kind of goddess, "Just a Teenage Gaea."

It is speculated that her mother was also a goddess or spirit of some kind.