Venomous Snakes  Black Mamba (Dendroaspis polylepis) portrait,
largest venomous snake in Africa. See more reptile pictures. Rod
Patterson/Getty Images  The fear of snakes, ophidiophobia, is
one of the most widespread phobias in the world. There are many
types of harmless snakes, but the venom from some poisonous
varieties can kill a person. The following snakes have the most
potent venom.  Reptile Image Gallery  Hook-nosed Sea Snake  The
worst of the worst is this four-foot-long waterborne menace that
lives along the coastlines of South Asia. The hook-nosed sea
snake doesn't attack humans often, but when it does, just 1.5
milligrams of its venom can cause death. Its preferred prey are
fish, which the snake paralyzes with its venom.  Russell's Viper
This three- to five-foot yellowish-brown snake is frequently
found in Pakistan, India, Southeast Asia, and China. The
Russell's viper preys primarily on rodents but will also kill
cats, squirrels, crabs, and even scorpions. Its bite causes
pain, swelling, and blee