What’s the most dangerous animal that has ever lived?

Half the human beings who have ever died, perhaps as many as 45 billion people, have been killed by
female mosquitoes (the males only bite plants).
Mosquitoes carry more than a hundred potentially fatal diseases, including malaria, yellow fever, dengue
fever, encephalitis, filariasis, and elephantiasis. Even today, they kill one person every twelve seconds.
Amazingly, nobody had any idea that mosquitoes were dangerous until the end of the nineteenth century.
In 1877 the British doctor Sir Patrick Manson—known as “Mosquito” Manson—proved that
elephantiasis was caused by mosquito bites.