Ravenloft was a D&D setting themed around the tropes of
gothic horror-- vampires, werewolves, ghosts, suspense, curses, dark magic. Basically it was "Dark Shadows: The RPG".
Which I'm pretty sure is actually a
thing in its own right.
Ravenloft had its own version of Frankenstein and his
monster, Dr. Jekyll and Mr. Hyde., Dr. Moreau, Dracula AND Vlad Tepes (two
different characters, one based off the vampire, one based off the historical
figure), Abraham Van Helsing and lots of inspiration from Poe, M. R. James and
other horror/macabre writers. Thankfully, the game avoided Lovecraftian
tropes for the most part (except for a land ruled by the octopus-headed mind
flayers) since unfathomable, oozing cosmic horrors don't really fit with the
very human horrors of gothic fiction.
It also had, er,
"mystic gypsies" called the Vistani-- though to be fair, the game did
admit these people were based on the gypsy archetype of old movies, not on real
Romani.
The March 1998 issue of Dragon magazine (#244) held a
contest called "Terrors from Above", asking readers to come up with
an original flying monster for Ravenloft.
The results were eventually compiled into a PDF book by the Kargatane,
an online group of fans who generated tons of cool original work for the
setting.
While the entries are pretty neat, there was a distinct
trend towards creatures that were basically just winged gargoyles/demons or some
slight ghost variant (2nd edition D&D had a glut of undead based on the
"incorporeal spirit that cannot rest because they have unfinished
business/were wronged in life/had some serious emotional issues" model).
But there are still a lot of weird original creations-- including a D&D
Mothman!
One of my favorites is the Cold Caller, created by Mathew
Sernett. Cold Callers are ethereal
flying fish that use haunting, flute-like songs to lure people out of their
homes on cold nights. The creatures,
which resemble pearlescent salmon with fluttering, gossamer wings, lead their
entranced prey out onto thin ice, where they inevitably crash through into the
frigid water. These unearthly fish then feed off the fear and panic of their
victims as they struggle, slowly succumbing to the numbing cold.
I've always liked creatures that gain sustenance from emotional
energy. They aren't necessarily evil--
heck, the Cold Callers are nothing but dumb animals. Yet these emotional
predators need the psychic terror of a sentient being to survive. The description
even says they must feed on fear to gain enough energy to produce eggs.
Cold Callers fit pretty well into the "gothic
dread" feel of Ravenloft. Like the previous Righteous Clay, they play on
the fear of dying or losing a close friend or loved one to the vagaries of
nature. There's not a malevolent force, or even any kind of sentience behind
this death-- just a stupid, hungry fish.
I like to think the Cold Callers were a deliberate creation
of the mysterious and malevolent "Dark Powers" that control Ravenloft.
A twisting of a natural animal to cause yet more fear and dread in the people
trapped in the gothic land.