"Dreugh are primarily found in the eastern areas of Tamriel," ZeniMax explains, "but can likely also be found anywhere coastal. Land dreugh can be found as far inland as Cyrodiil." If you've played Morrowind and Oblivion you've likely encountered earlier versions of the dreugh, and if not, well, what are you waiting for? Head past the cut for the clip and then to the official site to learn more.
[Thanks to Paul for the tip!]