The official “gillmen” in Hollow Earth Expedition‘s Mysteries of the Hollow Earth sourcebook are anthropomorphic fish people. They have legs, and are pretty unseemly things. I was originally going to ignore them, but a possible angle to the current campaign has given me a possible use for an aquatic race. I just don’t like these ones…

05b9db24b04505837d649cee3db2e738I decided I wanted something with a more Abe Sapien vibe from Hellboy, but I also wanted them to be alien; a tail was something I thought was needed.

The obvious choice was to go full merfolk… But all the merfolk images tended to be sexy mermaid crap.

Then I stumbled onto Ian McCaig’s on the left. Similar enough to the Abe Sapien look I wanted.

So I reworked the Gillman package into the Mermen package.


Ancient, mysterious, and the subject of intense superstition, merfolk are one of the more populous races in the Hollow Earth, but are rarely directly encountered. Their appearance ranges from truly alien — gilled, long tails, scaled, to strangely human. Some have even been rumored to have legs!

Physiologically, from the “waist” up they appear nearly human, but caudally they have long tails. Their faces are eerily human, but will large, dark eyes, gills to the sides of the head and neck. They have no apparent ears, but hear through their skin, using a form of echolocation. Additionally, they possess Ampullae of Lorenzini, like sharks, and can sense fain electrical fields, allowing them to find prey more easily. Some merfolk are known to wear jewelry about their bodies and it has been speculated that this may enhance this ability. Some have “hair” that look to be some kind of protective growth and tend to only be seen on the females.


Very little is known about the culture of the merfolk, other than they travel in “pods” of “schools” of a dozen to perhaps three or four dozen. They communicate through a complex tonal language that can be heard for tens of miles when they are underwater and is sometimes mistaken for whale-song by those from the Outer World. Some of the merfolk have been known to lure sailors to their deaths but hypnotizing them with certain frequencies and progressions in their songs.

They are romantic, impulsive, artistic, and philosophical, but they are also hardly pragmatic as a race in the highly competitive environment they live in can be.

They appear to believe in something called the “Great Deep” — an allegory for eternity. They claim to have been “created” by the Ancients that once populated “the World”, as most of the beastmen were.


There are some that claim to have talked to these creatures, and that some have learned the speech of other denizens of the Hollow Earth.

Mermen Zero Level Skills

All mermen are assumed to have at least zero level (see the sidebar in Secrets of the Surface World) in Athletics, Brawl, Melee, Performance, Stealth, and Survival

Mermen Characteristics

Starting attribute adjustment: +1 Body, +1 Dexterity, -1 Strength, -1 Charisma

Natural Advantages: Aquatic (double movement rate  in water, but half Dexterity (round down) and movement on land; Captivate: Can use Performance to entrance a target for the number of rounds equal to their number of successes over the target’s Willpower; Gills: can breath in water; Echolocation: can “see” without light; Electroreception: can sense electrical fields in water, +2 perception in water; Siren Call: This is a longer version of Captivate that can only be used in non-violent situations. The length of time is in minutes equal to the number of successes over the target’s Willpower.

Normal Flaws: Dry Skin (after an hour will take 1N damage for each hour not hydrated.), Primitive