What are some of your favorite animals that are considered dangerous? I'm not talking something to have as a pet, but just an animal you find fascinating or cool. Sydney Funnel-Web Spider (creepy picture warning): Spoiler ^ One of the most dangerous and vicious animals in the world. They can bite several times in a few seconds and their venom is highly dangerous, some of the most lethal in the world. Another favorite of mine is the Blue-Ringed Octopus.