Ocubeasts (click for more info)
Ocubeasts are small, fragile lesser demons usually invisible to the mundane (i.e. anyone of a non-magical nature will not see them). This makes them perfect as spies. Most magic users of a questionable alignment make use of them but also greater daemons emply them as their eyes and ears in the mortal plane, seeing through their eye (ocubeats only have one eye).