King Cobra
These snakes are famous as being the biggest venomous serpent in the world. The typical specimen is 12 to 15 feet long, but it is not uncommon to find 18-foot king cobras. They are found in a wide band that extends from Southern China through Southeast Asia, as far east as the Philippines and as far west as Bangladesh and India. Within this area, they are mostly found in highland rainforests. Their bite can deliver a substantial amount of neurotoxic venom (meaning it attacks the nervous system), and it is not unheard of for cobra bites to fell elephants. The king cobra is active during the day, and an adept swimmer and tree climber as well. The snake is fairly intelligent, however, and it does not aggressively seek conflicts with humans. With a little caution, they are easily avoided. Should you encounter a king cobra, remember that it bites downwards. Stay out from underneath its downward biting arc, and make no aggressive moves towards it.
Malay Pit Viper
This is a reddish-pink snake with the telltale facial markings of a pit viper: the pit sensory organs located between the eyes and the snout. They tend to be between 2 and 3 feet long. As a pit viper, the snake's venom is hemotoxic (meaning it attacks the flesh), much like its distant and more familiar cousins, the rattlesnake or cottonmouth of North America. It is found in lowland jungles across Southeast Asia. As a bad-tempered and aggressive snake, it is prone to bite first rather than leave, and should be treated with great respect and caution at all times.
Fer de Lance
This poisonous snake is a resident of rainforests from Venezuela through to northern Argentina, including the Brazilian Amazon. It is sometimes even seen in Central America. It is between 6 and 7 1/2 feet long, with a color pattern of dark brown and light brown bands. It is reputed to be the deadliest snake in South and Central America, and a typical bite yields twice as much venom as is necessary to kill a human. The Fer de Lance live on the forest floor, and are nocturnal hunters who pursue small birds and rodents.
Poison Arrow Frog
Frogs might seem harmless, but the bright colors of this South American frog should warn you otherwise. The tiny frogs are about the size of a big thumbnail, but each one packs enough venom to kill roughly 100 people. They are extremely toxic. They are difficult to properly identify, however, because their colors range from red to blue to yellow, and the males can even change colors. The best warning you're likely to get before you squash this deadly frog is, in fact, that its colors are changing. The frog gets its name from the use South American tribesmen have for them, namely to provide poison for their arrow and dart tips.