Tiamat, The Dragon Queen

Tiamat  was the evil dragon goddess of greed and queen of evil dragons. Tiamat was also the eternal rival of her brother Bahamut, ruler of the good metallic dragons.

Description 

Tiamat was a unique chromatic dragon, who had one head for each primary color of the most common species of chromatics (black, blue, green, red, white). Each head was able to operate entirely independently of each other and had the powers of a member of the respective race of dragonkind. Her body also had traits in common with a wyvern, including a long tail tipped with a venomous stinger. She also had three main avatars. The Dark Lady was a woman with long dark hair and completely black eyes. She always wore dark robes and frequently had a seductive smile on her face.
The Chromatic Dragon was a dragon with stubby legs and five heads that could be any combination of head belonging to a chromatic dragon, the skin of each merged into three stripes -- blue-green, gray and purple before they merged again into brown skin that covered her tail.
The Undying Queen was a dracolich version of The Chromatic Dragon.

Worshipers

Tiamat has had a large group of follwers known as the Cult of the Dragon  that worship her as their diety. Many evil dragons have worshiped Tiamat since their species first appeared on Toril,and kobolds believed she was their creator, and although they didn't worship her as god they revered her as their creator.

Banishment

In 1489 DR, many of the Cult of the Dragon prepared a plan to prepare an artifact known as the Mask of the Dragon Queen which would allow Tiamat to enter into the mortal realm.  The cultists were eventually stopped, and Tiamat was once again banished to the Nine Hells.