“Tiamat is a supremely strong and powerful draconic goddess in the Dungeons & Dragons role-playing game. The name is taken from Tiamat, a goddess in ancient Mesopotamian mythology who is substantially different (and does not have multiple heads).
Tiamat is a queen and mother of evil dragons and a member of the default pantheon of D&D gods. Her symbol is a five-headed dragon.
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”. D&D Wiki