The four venomous snake species responsible for causing the greatest number of medically significant human snake bite cases on the Indian subcontinent (majorly in India and Sri Lanka) are sometimes collectively referred to as the Big Four. They are as follows:[1][2] Russell's viper, Daboia russelii Common krait, Bungarus caeruleus Indian cobra, Naja naja Indian saw-scaled viper, Echis carinatus