Mushrooms

The fungus Ophiocordyceps unilateralis is able to take control of ants.

An excerpt from the article 22 facts about Mushrooms

Fungi of the genus Cordyceps are parasitic fungi, living on animals - on insect larvae or spiders - using them as a source of protein. Ophiocordyceps unilateralis produces a substance that crosses the blood-brain barrier and paralyzes the nervous system of ants. These insects become free - zombie ants - are completely controlled by fungi.