Baphomet
Demon Lord Baphomet was encountered at the Temple of Dalva-Nar in Dragonslayers.
His physical form was temporarily destroyed by Lily with the Pike of Heroes, before His Unholiness could cast a single spell or swing his Halberd of Death.
His Unholy Shrine was described in GM Notes:
Top level is painted black within. A single skylight of blue-tinted glass (vision -4). Pentagram in red chalk on the floor, and wooden pole sticking out of it. A chain, and Sashi, abused.
Bronze candlestands, black scented candles -- and a 10' statue: humanoid with female breasts, shaggy lower torso and legs, hooves, bat wings, horned goat head with fangs and a beard, and a real flame atop his head, one arm held aloft, curved talons, the other open handed below.