The Green Beasts were created sometime before the Shadow Lord's first invasion of Deltora. Exactly where they fit into the Shadow Army is unclear, but occasionally some would escape from the Shadowlands and prowl the Dread Mountain area.
A group of Dread Gnomes were hunting a Green Beast when Adin came to Dread Mountain to ask for the Emerald for the Belt of Deltora. The Gnomes captured him and intended to use him as bait for the beast, but their trap failed and the beast nearly killed their leader — Az-Zure —before Adin was able to slay it.
The Kin whom Lief, Barda, and Jasmine met never mentioned the Green Beasts when they spoke about the dangers of Dread Mountain, so it is possible the Green Beasts had gone extinct by this time or at least on Dread Mountain.
Green Beasts are large, bipedal green-scaled lizards with three-clawed hands and orange eyes. The scales on their bodies are thick enough to repel weapons, but their throat-scales are less durable and can be pierced by a spear, sword, or heavy arrow.