Tiamat

Tiamat is the queen of evil dragons and a member of the Untheric pantheon.

Like other Untheric deities, she was brought to Faerûn when the Imaskari planar barrier fell, allowing the avatars of the gods of their slaves to come to Faerûn via the astral plane.

She had a reputation amongst the people of the new state of Unther for battling with the other members of their pantheon and was blamed for every one of the many setbacks Unther experienced. In fact, Tiamat was much more concerned with expanding her influence over the rest of Faerûn, converting chromatic dragons to her worship. The first notable problem she caused was when she ate the dragon god Tchazzar who was worshipped by the people of Unther. Because she kept out of the affairs of Unther, her cult survived while the other Untheric powers became more tyrannical and destructive. This gave her the power to defeat Gilgeam during the Time of Troubles which threw Unther into chaos and helped dissolve the whole pantheon. Now she is a member of both the Faerunian pantheon and the Draconic pantheon, despite the fact that she lives on the same plane as the Mulhorandi pantheon. Being a member of these pantheons though has made her some enemies, including Bane and Ilmater.

Description
Tiamat has one head for each primary color of chromatic dragon (black, blue, green, red, white), and each head has the powers of a member of the respective race of dragonkind.

Tiamat was also one of the first deities to have Aspects, or lesser avatars. These Aspects may appear as powerful versions of her chromatic children or as versions of her own five-headed form.