So I decided to start my fortress in a haunted region. Digged a comfy little hole on the side of the hill, with the stockpiles on the ground level and the bedrooms, dining hall and workshops underground. Just didn't bother to wall the entrance which I cunningly made wide enough for everyone and their dog/cat to come through at once (well not quite, but you get the idea). Then, a cloud of nefarious ash passed by, huskifying some of the hapless wildlife. Excited and terrified (but mostly excited), I drafted a few dwarves and made them beat the everloving undead shit out of the one that approached them and wasn't covered in anything nasty.
One dorf got his face smashed in and another got sent to bed unconscious from his injuries. Everything seemed fine until an ash-covered kangaroo caught up to a fleeing Animal Caretaker. After he turned he began to rip the kangaroo to shreds above my fortress. I tried (in panic) to make my dwarves wall the entrance with something, which I still had cunningly left wide open in case there was no fun to be had. Nothing happened, until it came from the desert from the hilltop. Luckily I had some dogs to attack their former caretaker. Unluckily it didn't really matter since it eventually proceeded to kill all of the impromptu militia (except the unconscious one), chasing them to the underground dining hall. It returned briefly to the surface to bite my doctor to death, who I also drafted and ordered to die in the name of Armok. At this point, the thing had both it's legs and most of it's arms cut off.
As if this all wasn't like something out of an obscure horror movie already, the nearly limbless husk then proceeded to crawl it's way underground, through a long and dark corridor to the bed of the sole surviving dwarf who was slipping in and out of consciousness, so it could gnaw and shake it's helpless victim like a chewing toy for several pages worth of combat reports. This is why I play Dwarf Fortress.