Tiamat

Tiamat is a female Dragon and the only female Dragon King. She is the Blue Dragon known as the Chaos Karma Dragon, and is one of the few active Dragons in the series.

Appearance
A blue Western Dragon.

Plot
While Tiamat has yet to appear in the series, she was mentioned in Volume 8 by the Familiar Master as a candidate for a powerful Familiar. Issei will meet her in Volume 14 of the Light Novels and he will recruit her to be his Familiar even though she hates Ddraig because she was spurned harshly by Ddraig. She likes Issei as Ddraig's user and is happy that Issei is making Ddraig cry with the "Oppai Dragon song". She finds him interesting and likeable and totally detests Ddraig because of her history with him.

Powers & Abilities
Being a Dragon King, it can be assume that she is very powerful. According to the Familiar Master, she has Satan-level powers.

Trivia

 * According to Ddraig, Tiamat hates him.