text: what is the animal responsible for the most human deaths? if u get it right u got my vote fa sure. mosquitos are most definitely animals. they are part of the taxonomic kingdom animalia.  many of the respondants are correct. mosquitos have caused more human deaths than any other animal because they spread the parasites that cause malaria.   rats spread the parasites that carry the bacteria that cause bubonic plague but malaria has killed more people than plague.