Some places have quite a few of them, from my defunct scavenger hunt thread K'na Tha has an Esanguine Soul and Dark Adder Empress, as well as a Murderain. The Grey King and the Dread Crystal Spider in the Wheel Clan also spring to mind, and naturally the Stillwater Giant. I think the Ancient Bear (or maybe it's called something else) at Gorgoth Pass may also be unique, and Treat in the Boil is pretty unique for being a gross snake monster. Some enemies, while not unique, are only found in small numbers at specific locations - e.g. Stygian Ghouls at the Ancient Maze. I guess there's probably a lot more, but they're all that immediately spring to my mind.
While it's not a unique enemy per se, I always found it interesting that the developers decided to make the Kite Shaman at the Crash Site much larger than most.
The guy at the castle has V.O, I believe (at least for an initial taunt) which is sufficiently unique.
Personally, I find it often helps to read through the first few posts of a thread before responding. I guess we can't all be cavalier madmen like you Vorak.
I'm terms of more unique enemies, I suppose Scratch and Ol' Bessie are unique enemies you can fight. Still, they're not exactly intimidating. Also, the Temporal Crusher.
I just found this little guy: An ethereal level 40 Bunny, same stats as the Vorpal Bunny it would seem. It's a little off the beaten path at K'na Tha - following the first indoors that you're teleported to after hitting the first brazier, when you head back outdoors there's a few places where you can jump over the wall. If you explore outside the complex that's where you'll find the little chap not far from one of the walls (if people are wondering why the to hit % is so high I had to paralyse him to take the picture). These are the kind of mighty rewards you reap from excessive secret hunting in a decade+ old game. There's also a small sprite Greater Gowrath at K'na Tha that I don't think has been mentioned (it has the same coloured sprite as a Greater Gowrath compared to a Lesser Gowrath and is labeled as one as well), but that's a rather more boring reveal.
There is the Lord of the Damned in the Ashbury Castle, or at least that's what I think his name was. I do believe there is a little dragon of some sort in Blackroot too, which can be found near the railway tunnel if you walk past the train, following its rail out of the town. Not completely sure if either is unique, though.
Lethe Wyvern, he actually does poison your brain, as per lore. His to_hit script permanently damages victim's IN, it won't even be marked red. There's absolutely nothing you can do about it. But at the point you get to him, you can probably smack him dead in a couple of hits.
