Mab

Mab has been called the Queen of Air and Darkness. She is easily among the most powerful beings in the dresdenverse. She has shown her power by performing great feats of magic with slight effort and has shown her intentions through her ways of punishing those who have betrayed or displeased her. First introduced in Summer Knight, she has purchased the use of Harry's services since his godmother the Leanansidhe sold the debts Harry owed her. When Leanansidhe came back to the Winter Court with a powerful athame, Mab forced her to sell Harry's debt to her to keep the balance in the court.

She is Maeve's mother, the Winter Lady.

In Dead Beat Mab was shown to have the athame from Leanansidhe on her hip. She possessed it because she locked the Leanansidhe away for a time until she could be shown to have respect again to the queen.

As of Proven Guilty, both Lily and Maeve have expressed a concern that she is going insane. In Small Favor she does not speak for herself during most of the book but instead uses the Grimalkin as her "voice". When she does speak, it is described as razor sharp and shakes the area where Harry is, making his nose and ears bleed. Harry's reasons that the cause of this condition is because of her fury over the attack on Arctis Tor in Proven Guilty.