Set

Alignment: Lawful Evil
Domains: Law, Evil, Knowledge, Death
Symbol: Black Ankh of Set
Garb: Kilt, sandals, and ceremonial head-dress (beast mask), Black Ankh of Set
Favored Weapon: Quarterstaff, spear, poisoned weapons
Typical Worshippers: Evil power-seeking humanoids, evil monks, assassins
Set is a greater god, worshiped on many planes in many forms. He most often appears as a scaled humanoid with the head of a jackal. He is utterly dedicated to the orderly spread of evil and oppression. His symbol is the coiled cobra, though any snake can be used to represent his power. His temples are filled with enormous serpents, always poisonous. His skin is poisonous to the touch. He makes his home in the Nine Hells.
Organized groups of assassins are known to be dedicated to his worship. His priests carry staves worked on one end into the head of a cobra. The cobra head is often tipped with steel fangs coated with poison. His clerics often carry a stylized black spear, representing the Spear of Darkness he carries. Many of his worshippers tattoo themselves with serpents or cobras.
Why's he not worshiped in the Valley? Oddly, because both Thyr and Orcus say no. Thyr wants a slightly less brutal theocracy, while Orcus has laid claim to the role of "resident evil guy". Set is worshiped right across the continent however, particularly north past the Jungle. There's variations on Set across the multiverse, and scholars agree it's probably all one god, shaping himself to appeal to different worshipers in different places. Snakes and ankhs here, spiders and lanterns there.