Some very, very good ideas.
But how dare I open this discussion without mentioning MY favorites. Where was my brain last night?
Some of these beasties may come from "other" games, as I have just started HARP and my RM days are barely remembered. But I do have some that cross game systems and always find a way into my worlds, if not my campaign:
UNDEAD. Yep. I'm a zombie lover (GreenRipper, if he's reading this, can attest to that!!
) I love hordes of zombies and skeletons, the ghouls attacking from sepulchres, the more rotten and skeletal the undead the better!! I also love undead versions of classic monsters such as orcs, trolls, ogres, etc. And undead dragons are just good fun!!
TROLLS For some reason, the D&D (AD&D?) Troll is one of my favorite monsters from THAT system. I also used to enjoy the heck out of Trolls in MERP, and I feel I will also like them with HARP just as much.
SLIMES Gotta have slimes and jellies, and the occasional ooze. I use them sparingly, if at all, but when used it is usually an encounter well remembered!!
DEMONS Well, I haven't used them yet, but I plan on it!!
There are many, many more but those are off the top of my head.