12. Common death adder

Common death adders are found across coastal areas of southern, eastern and northern Australia. They are recognizable thanks to their broad, triangular heads, short, thick bodies and thin tails. Common death adders are ambush predators and wait for prey — including frogs, lizards and birds — under leaves until they are ready to strike. 

Bites to humans are rare and normally involve a person stepping on one by accident. Their venom causes paralysis and can lead to death: Before the introduction of antivenom in the 1950s, about 60% of bites were fatal, according to the Australian Museum. The most recently recorded human fatality from a common death adder bite was in 1930.