The most deadliest animal in the world on land is the Cape Buffalo and in the water and also when it gets on land the other deadliest animal is the Saltwater Crocodile.
Other deadly animals are Cone Snail, Golden Poison Dart Frog, Box Jellyfish, Pufferfish, Black Mamba and the Tsetse Fly.
Not all of them are considered to be animals but some are insects however those are all deadly to humans.
Also a human is another deadly animal to humans in the world because of murders.
Mosquitoes actually kill more humans per year than animals do.
A mosquito kills around 1 million humans per year because of the virus they spread when they bite a human.
Most mosquito bites are nothing to worry about but if you do get bitten by a mosquito you should get tested for the Zika virus, West Nile Virus, Chikungunya Virus, dengue, and malaria.
Those viruses that spread from mosquitoes can easily kill someone especially if they already have health issues or are older.
Make sure to avoid being around mosquitoes when possible and also use mosquito repellent etc.