- Komodo dragon, Varanus komodoensis
- 2.59/79–91 dimension(s)
- Indonesia ()
With adult males averaging 2.6 m (8 ft 6 in) long and weighing 79–91 kg (175–200 lb), the largest species of venomous lizard, as well as the largest extant lizard species overall, is the Komodo dragon (Varanus komodoensis). Although scientists have long known that in the wild state its saliva contains pathogenic bacteria, it was only in 2009 that this species was also shown by Dr Bryan Fry to possess a pair of true venom-secreting glands, present in its lower jaw, with this trait shared with all other anguimorph lizards and being the same venom glands as those in the iconic Gila monster (Heloderma suspectum). Otherwise known as the Komodo monitor or ora, the Komodo dragon is found on the Indonesian islands of Komodo, Rintja, Padar and Flores.
Adult female Komodo dragons are slightly smaller, growing to an average length of 2.3 m (7 ft 6 in) and typically weigh 68–73 kg (150–160 lb).
The Komodo dragon's extinct giant relative Varanus prisca (Megalania) was, at 4.5–6 m (15–20 ft) long, the largest terrestrial lizard ever, and likely too the largest venomous animal to have ever lived on Earth.
Gila monsters, native to arid regions of southern USA and northern Mexico, are the most venomous lizards, with LD50 (lethal dose in 50% of recipients) values for its venom as low as 0.4 mg/kg recorded when administered intravenously in mice.