In a recent adventure with my group of players, I used the following passage as inspiration for an encounter in a mountainous region. They came across an isolated mountain village, where a villager had disappeared, or more exactly, had been taken by the Hollow-Men:
“The Hollow-Men live in solid rock and move about in it in the form of mobile caves or recesses. In ice they appear as bubbles in the shape of men. But they never venture out into the air, for the wind would blow them away.
They have houses in the rock whose walls are made of emptiness, and tents in the ice whose fabric is of bubbles. During the day they stay in the stone, and at night they wander through the ice and dance during the full moon. But they never see the sun, or else they would burst.
They eat only the void, such as the form of corpses; they get drunk on empty words and all the meaningless expressions we utter.
Some people say they have always existed and will exist forever. Others say they are dead. And others say that as a sword has its scabbard or a foot its imprint, every living man has in the mountain his Hollow-Man, and in death they are reunited.” – from Mount Analogue, by René Daumal
Here is my creature adaptation for the Hollow Men:
They appear as slightly shorter than man-sized shadows moving along the ground or wall or roof of the cave. To attack the PC’s they will leap, and take on a form similar to a shadow, and they will throw their bodies at the PC’s, attempting to pull them into the rock. They hit for 1d8+3, with a chance to knock the PC’s over if the PC’s fail a saving throw vs. paralysis. The PC’s will become Hollow Men if they lose all HP, being sucked into the void-space that the Hollow Men occupy.
They have 3 HD, and 1d6+2 will appear. AC: 2. No treasure hoard. However, any items belonging to people who have become Hollow Men will be found in the vicinity. The Hollow Men are only found in mountainous regions, especially caves and glaciers.
I’ve included these other passages to further describe the hollow-men, and try to illustrate what an encounter might be like.
More from Mount Analogue:
“He strikes with his hammer, and his hand sinks into a hole. There is a hollow under the rock. He breaks the crust around it and sees that this hollow has the shape of a man: a torso, legs, arms, and hollows in the shape of fingers spread in terror; he has split the head with one hammer blow. An icy wind blows over the rock. Mo has killed a hollow-man.” – 74
“Watch out for the hollow-men. They will avenge his death. They cannot enter our world. But they can come up to the surface of things. Beware of the surface of things.” – 74
“The hollow-men have taken your brother. They have changed him into a hollow-man. He will try to escape them. He will try to escape them. He will search for light at the seracs of the Clear Glacier. Put his medal around your neck along with yours. Approach him and hit him on the head. Enter into the form of his body. And Mo will live again among us. Do not be afraid to kill a dead man.” -74-75
“Ho looks as hard as he can into the blue ice of the Clear Glacier. Is it the light playing on the ice, do his eyes deceive him, or is he really seeing what he sees? He sees silver shapes with arms and legs, like greased underwater divers. And there is his brother Mo, his hollow shape fleeing from a thousand hollow-men in pursuit, but they are afraid of the light.” – 75