The Thorny Devil (Moloch horridus), also known commonly as the mountain devil, thorny lizard, thorny dragon, and moloch, is a species of lizard in the family Agamidae. The species is endemic to Australia. It is the sole species in the genus Moloch. It grows up to 21 centimeters (8.3 inches) in total length (including tail), with females generally larger than males, and can live for 15 to 20 years.
Most of these lizards are colored in camouflaging shades of desert browns and tans. These colors change from pale colors during warm weather and to darker colors during cold weather. These animals are covered entirely with conical spines that are mostly uncalcified.