Queen Hylda is the Queen of the Goblins, and is introduced in the book, Lodestar.
*SPOILER ALERT, THIS CONTAINS PARTS OF THE STORY FROM LODESTAR.*
When Sophie is announced to go to the Peace Summit, Queen Hylda requests to meet with her regarding the Summit. She gives Sophie a list of things that she wants Sophie to support her on, this includes things such as "She wants the ogres to turn over all their weapons and agree to stop any sort of offensive-or defensive-training, wants them to surrender the borderlands they share with the goblins, and wants King Dimitar to turn over the ogre that killed Brielle."