The Gila monster, Heloderma suspectum, is a species of venomous lizard native to the southwestern United States and northern Mexico. A heavy, slow-moving lizard, up to 60 centimetres long, the Gila monster is the only venomous lizard native to the United States, and one of only two known species of venomous lizards in North America, the other being its close relative the Mexican beaded lizard. Though the Gila monster is venomous, its sluggish nature means that it represents little threat to hum ...