Monmouth is a wizard who first appears in Dandelion Fire.
Monmouth's father apprenticed him to dark wizards in the service of Carnassus for some time before he met Henry York. The wizards despised Seventh Sons, "...because they have a right to be touchin' what they touch!" (according to Fat Frank), unlike wizards who must usurp the powers they wield. Monmouth hid from them his birthright as a Seventh Son to avoid persecution. Some time into his apprenticeship, Monmouth watched Namiane enter the hall of Carnassus as a hag, weak and frail, and begin leeching the life from all around her until she grew stronger than all of Carnassus' wizards together. Monmouth learned of "Mordecai's Son" through Namiane's orders to the wizards to hunt and slay him. Monmouth instead rescued Henry from the other wizards and vowed to help him destroy Namiane as Mordecai had once done.
Monmouth is described as a slightly-built, fair-skinned youth with jet black hair and grey eyes. He received his Second Sight from an Aspen tree, and thus bears the flaming mark of an aspen leaf on his right palm and is considered a "Green Man" as are Henry York Maccabe and Mordecai Westmore.