The frill-necked lizard, also known as the frilled lizard or frilled dragon, is found mainly in northern Australia and southern New Guinea. This species is the only member of the genus Chlamydosaurus. Its name comes from the large frill around its neck, which usually stays folded against the lizard's body. It is largely arboreal, spending the majority of the time in the trees. The lizard's diet consists mainly of insects and small vertebrates. The frill-necked lizard is a relatively large lizard, averaging 85 cm in length.

The neck frill is supported by long spines of cartilage which are connected to the jaw bones. When the lizard is frightened, it produces a startling deimatic display: it gapes its mouth, exposing a bright pink or yellow lining; it spreads out its frill, displaying bright orange and red scales; raises its body; and sometimes holds its tail above its body.

The frill-necked lizard does not have a standard colour; however, it is characterised by a body that is darker than its frill. It is only species in the genus Chlamydosaurus; however, the range of colour variation in the species has led some scientists to suggest there is more than one species.

The frill-necked lizard is found mainly in the northern regions of Australia and southern New Guinea. The lizard inhabits humid climates such as those in the tropical savannah woodlands. Being mainly arboreal the lizard ventures to the floor only in search of food, or to engage in territorial conflicts. The arboreal habitat may be a product of the lizard's diet, which consists mainly of small arthropods and vertebrates (usually smaller lizards). However, the trees are most importantly used for camouflage. There is not one standard colour: rather, colouration varies according to the lizard's environment. For example, a lizard found in a dryer, clay filled environment will most likely have a collage of oranges, reds, and browns; whereas a lizard found in a damper, more tropical region will tend to show darker browns and greys. This suggests that the lizards use their habitats for protection in the form of camouflage.

The species' main threats are eagles, owls, larger lizards, snakes, dingoes and quolls.