Introducing, in order of appearance:

• Oya the Red, Queen of the Sisters of the Flame
• Sadira Nasri, representative of the Confederation of Families
• Tatiana Tristei, Empress in Exile and Lady Regent of Summer and Winter
• Cerine Celador, Queen of the Bright Court
• Bryony Rosemerrow, Princess of the Circle of Roses
• Isabeau Martin, Lady of the Sibyllae
• Ymir Freyasdottir, Queen of the Bloody Court
• Ondine Coldwater, Director of the Hudson Bay Conservation Society (formerly the Drowned Kingdom)
• Moon Heart, Queen of the Daughters of the Earth
• Tempest Starling, Speaker for the Twilight Chorus
• Gwendolyn Adair, Commander of the Thorn Order

Don't let the titles fool you, every last one of them is a Queen, through and through.

EDIT: There was some confusion as to who's who, so I made a name chart from this page!