That would be Zoso
ZOSO
Alford's Occult Crimes Investigations "Signs and Symbols of Occult/Devil Worship" list also includes a sigil that looks like the word "ZOSO" with the interpretation: "Demon: 3 headed dog that guards gates to hell." "ZOSO" has been popping up in various so-called manuals on "occult related crime" for years. It is usually defined in these manuals as: "ZOSO: The three headed dog that guards the gates of Hell."
My first tattoo.