The emerald tree monitor (Varanus prasinus) or green tree monitor, is a small to medium-sized arboreal monitor lizard. It is known for its unusual coloration, which consists of shades from green to turquoise, topped with dark, transverse dorsal banding. This coloration helps camouflage it in its arboreal habitat. Its colour also makes the emerald tree monitor highly prized in both the pet trade and zoos alike.
The emerald tree monitor is about 75–100 cm (30–39 in) long with a slender body that helps it support itself on narrow branches. It uses its prehensile tail and long claws to grip branches. Unlike other varanids, this monitor defends its tail rather than lashing with it for defense when threatened. The soles of the feet of the emerald tree monitor have enlarged scales which aid the lizard when climbing.