Cleon
Legend
There's also an original D&D version in the Blackmoor Supplement (1975) and another version in Fritz Leiber's Lankhmar (1996), but I don't have either of those sources immediately to hand.
Still, I might dig them out just to see if there's any useful extra data in them.
I checked the two previous versions and they did add some interesting extra data.
The original Blackmoor version could drain energy levels - it was literally a vampire. I'll edit this post to include the relevant text, but it's on my main computer and I don't want to access it at the moment because of an inconveniently positioned cat.
The Lankhmar version is pretty much the standard AD&D version, but what's interesting about it is that it was listed in an adventure because it's an alternative form of a shapeshifting humanoid race - so we've got yet another creature to add to our Lycanthropes and Shapeshifters thread!