Here's a link to a cool story, including a video, of fungi that parasitize insects and turn them into "zombies."
Although these fungi don't actually reanimate dead insects, they do have the ability to influence the behavior of their hosts. A fungi-infected ant, for instance, will engage in behaviors that will make it more likely to spread the fungus to other members of its colony. Imagine if--when you were sick with the flu--you had an uncontrollable urge to walk up to people and sneeze on them!
Although the specific fungi mentioned in the article are newly-discovered, this phenomenon has been known in insects for a long time. In addition to fungi, some viral diseases are also able to affect similar zombie-style behavior in their insect hosts. Luckily, none of these diseases are able to infect humans!