So, with DF2010 we finally have the much anticipated Random Beasts. They are often super cool, sometimes difficult to imagine, and occasionally over/underpowered. It is pretty clear, however, that Toady isn't done with them. This thread is aimed at discussing what the "categories" of random beast could be, both as speculation, and as a form of suggestion based around what the consensus is about what each of the possible categories might mean. Remember that everything posted here is someone's opinion, so offer constructive criticism if you like
My own vision is as follows:
Demon: Much like the worldgen demons are now. A <something> "twisted into humanoid form", necessarily having wings. Horns and hooves might also be something to think about. I was sort of disappointed the first time I breached hell and rather than the demons from worldgen, I got a cavalcade of...well...mostly dinosaurs made of steam. It wasn't that they weren't plenty cool, just not the kind of cool I was hoping for. Should be able to take over civs, and be strongly motivated to do so. Evil.
Devil: Same role as demons, but possibly containing some other trait. I imagine devils being smaller, more plentiful, and wingless versions of demons; hordes of them marching about the floor of hell. Tails a plus. Evil.
Titan: Again, I envision a humanoid, but this time gigantic. Possibly constrained to anthropomorphic animal/animals combinations. Should be able to take over civs if spheres line up. Good/Neutral/Evil.
Gargantuan: This is the name I would give beasts like the current titans. Their unifying trait is that they are big. I would possibly constrain them from using inorganic material templates, so that they essentially become big randomized animals. Neutral.
Colossus: Gigantic humanoid made of <randommaterial>. Maybe only metals. Probably a good idea not to allow Adamantine/Slade as a material.
Golem: Same as above, but not gigantic.
Forgotten Beasts: No changes here (except to prevent getting attacked by giant intelligent blobs of vomit...though come to think of it that is pretty dwarfy). The FB's are nice because you really don't know what to expect at all.