Which is the most poisonous reptile known?

This question has more than one answer depending on what you mean. 'Poisonous' refers to something that is toxic if eaten or drank, and there are poisonous reptiles - some snakes, such as some gartersnakes (Thamnophis spp.) and Japanese keelbacks (Rhabdophis tigrinus), sequester toxin from their amphibian prey and so would poison you if you ate them. However, most dangerous snakes and lizards are venomous, meaning that if they were to bite you their saliva (venom) would be toxic. The snake with the most toxic venom (meaning that it would take the smallest amount to kill 50% of test mice into which it is injected) is the Inland Taipan (Oxyuranus scutellatus) of Australia. However, this species is not considered very dangerous because it lives in area where almost no humans live. The snake that kills the most people each year is the Russell's Viper (Vipera russelli), which has fairly toxic venom and lives in an area where it commonly comes into contact with humans.