Xalgumath
Xalgumath is of the Ones Within, a minor deity of selfishness, greed, and dominance. He was once quite prolific, and is the father of all Tieflings, though he was defeated and chained by the other deities for offering aid to Bach'thal in The Devil's Treason. Legend says that he was bound within the confines of a crystal orb, known to lore as the
Stone of Xalgumath.
Some Tieflings have rebranded Xalgumath into a patron deity despite his negative connotations, but such voluntary devotion is completely divorced from the original entity. Moreover, that entity still wields some power, and continues to influence mortals today, but to a far lesser degree.