Tyranny of Dragons
Tiamat is the five-headed queen of the evil chromatic dragons. She has one head for each customary color of chromatic dragon (black, blue, green, red, white), and each head has the powers of a member of the respective race of dragonkind. Her body is a blending of various chromatic dragon forms with an appropriately multicolored hide. Her body also has traits in common with a wyvern, including a long tail tipped with a poisonous stinger.
Tiamat has also been known to manifest as a dark-haired human.
Like most other draconic deities, Tiamat is the offspring of the dragon creator deity Io. She is the eternal rival of her brother Bahamut, the ruler of the good metallic dragons. It is hinted that her overt hatred toward Bahamut has developed, over a vast period of time, into a twisted lust for her brother as well. She dwells in Avernus, the first layer of the Outer Plane of Baator (also known as the Nine Hells).
Three Baatezu nobles (granted to her by Bel) serve Tiamat and command her armies on Avernus. Malphas leads 40 companies of abishai, Amduscias leads 29 companies of abishai, and Goap leads three companies of erinyes. With Pearza of the Dark Eight, Tiamat created the first abishai.
Tiamat has three children. An-Ur, the Wandering Death, wanders the Ethereal Plane, devouring whole demiplanes; it supposedly sprang into being from Tiamat’s “first breath”, which may have been the name of one of her consorts, though An-Ur resembles no draconic species, except perhaps the ethereal moonstone dragons. Dhakoth, the Corruptor was born on the Negative Energy Plane; its father is unknown. Mordukhavar, the Reaver is the offspring of Tiamat and Cantrum of the Dark Eight. Kurtulmak is also her son, at least according to some myths.
Periodically, Tiamat has battles with the Babylonian god Marduk, who dwells in Arcadia. She also battles Bahamut, her lawful good counterpart. Heironeous and Moradin also consider themselves her enemies. Tiamat claims not to need allies, although she has many pacts with Bel and with lawful evil deities such as Hextor.
Tiamat is a greedy, vain, and arrogant goddess who embodies all the strengths of evil dragonkind, and few of their weaknesses. Tiamat is most concerned with spreading evil, defeating good, and propagating chromatic dragons. She never forgives a slight. Although she is not averse to razing the occasional village, her true schemes are subtle and hard to detect. She has been compared to a puppeteer manipulating her creations from within shadows.
The Queen of Evil Dragons demands reverence, homage, supplication, and tribute from her subjects. She is sometimes called “Her Dark Majesty” or simply “Dark Queen”.
Few humans or other humanoids worship Tiamat, but her children, the chromatic dragons, all acknowledge her sovereignty. Blue and green dragons obey her most readily. The grotesque reptilian creatures known as the spawn of Tiamat worship her as their mother. Kobolds may also revere her as their progenitor.