Mogget is the bound form of Yrael, the Eighth Bright Shiner. He usually appears as a small, white cat, but can also appear as an albino dwarf, although not in the presence of an Abhorsen unless he has his or her permission, ever since he was forbidden by Jerizael, the 48th Abhorsen. It is this form he appears in to Terciel, with whom he shared a close relationship.
His binding is a red leather collar or belt with a miniature bell attached. This collar is one of the last known Wallmaker relics. The bell attached was originally Saraneth, but was replaced with a miniature Ranna at the end of Sabriel. At the end of Abhorsen, Sabriel replaced the bell with Belgaer, to allow Mogget freedom of choice. Mogget occasionally attempts to persuade other characters to remove his collar, which would set him free. Upon binding, he presents his binder with a ring; the ring is a replacement collar for use in the event that Mogget is released. When released, he assumes his true form as Yrael, a tall, slender, man-like form of white, hot light and an incredibly huge mouth. When he is free, he is bent on destroying the Abhorsen and all his/her descendants as an act of revenge for his enslavement.
After his release, Mogget disappears to the North, but still returns occasionally to visit Sameth, with whom he has a strange friendship. It is this friendship (and the promise of fish) that leads him to help in the fight against Chlorr in Goldenhand.