Is a bacterium a plant, an animal, or other? If it's classified as an animal then it gets my vote. Otherwise I pick human. Mosquitos are responsible from many more deaths than are humans but they aren't dangerous in and of themselves, are they?
Bacteria have a whole kingdom to themselves.
The last I heard, there were five kingdoms and two super-kingdoms:
Superkingdom Prokaryota:
Cingle-celled organisms with no cell nucleus. Includes the Bacteria, and possibly some other things even more primitive.
Superkingdom Eukaryota:
Organisms with cells with nuclei. Includes:
Protists: All single-celled eukaryotes, and some multi-celled ones as well. Includes some things like amoebas and algae that were formerly classified as animals or plants, but it was eventually decided the boundaries were too imprecise. What do you call a single-celled organism that uses photosynthesis, and can swim around using its flagella trying to avoid predators and catching food?
Plants: Multicellular organisms that use photosynthesis, and have some other defining characteristics I can't remember off hand (possibly "being made from cellulose").
Fungi: Once classified as plants, but then it was realised they are as different from them as plants are from animals. And later discovered that they actually have more in common with animals than they do with plants.
Animals: Move. Eat. (Probably more to it than that).
Disclamer: it is atleat 7 years since I was taught this, and am writing from memory. I may have missed something important or made a mistake. (Or the definitions may have changed as well).