Keep that mouth away from me!

Endemic to islands of Indonesia, the Komodo Dragon is the largest lizard in the world. Due to their large size, and the virulent strains of bacteria living in their mouths (close to 60 different strains can be found in just one lizard's mouth at one time), they are the top predators of their ecosystem. In fact, one bite from one of these animals can be lethal! 

And they will eat ANYTHING! Birds, invertebrates, other reptiles, monkeys, wild boar, you name it.
In the wild, these animals are mostly loners, and come together only for eating and reproduction. But, if a female Komodo is not able to find a mate for an extended period of time, the species is capable of parthenogenesis, which means they can produce eggs that will develop into offspring without mating. 
Thanks Alexa for suggesting this ruthless carnivore and National Geographic for video evidence.