An Army of Creatures
An original editorial by Sarah Parks
I have a brief theory about what is going to come in the next book(s). In GoF, when Voldemort comes back he gives this speech about who will join him: dementors, faithful death eaters, giants, and "AN ARMY OF CREATURES WHOM ALL FEAR!" (pg 651).
I haven't read any discussion over this topic, and I don't know why because it seems like real big news to me. I mean why all the secrecy, why not just come out and name these creatures? I think it's because they will turn out to be heliopaths, which we hadn't yet heard of at that time and which the general wizarding population doesn't know exist.
As mentioned by Luna in OotP, heliopaths are "spirits of fire," "great tall flaming creatures that gallop across the ground burning everything in front of [them]" (pg 345). Luna even says that Fudge has an "army" of them. Note the usage of the word army by both Voldemort and Luna. They are probably dark creatures once controlled by the ministry (and kept secret) but, like the dementors, will join Lord Voldemort.
Even if this theory doesn't fit, I'd like to hear some other ones about what Voldemort's creature army will comprise.