Any of several kinds of large wasp. The types of hornet that would have been familiar in the Westlands of Middle-earth were less emphatically striped than their smaller wasp cousins, and built communal nests around a queen hornet.

In comparison with ordinary wasps and bees, hornets are especially notable for their size: a typical European hornet can grown to 3.5cm in length (or a little under 1½ inches) and other kinds can grow larger still. When Bilbo and the Dwarves were led by Gandalf into the bee-pastures of Beorn, they encountered honey bees that were even larger than hornets, implying that those bees might have been at least 4cm in length (perhaps two inches or even more).