Three Other Realms from the Rules Cyclopedia

From the Rules Cyclopedia, page 176:

Elementals live in towns and cities on their own worlds. Both the worlds and the building materials are made entirely of pure elemental material, in solid, liquid, or gaseous form. In the universe of its own plane, each elemental race occupies thousands of worlds. The elemental races are far older than humankind, and more civilized in many ways. They have art forms for six senses. 

Entire universes comprised of one element. A never-ending mass of earth stretching in all directions - not just to all compass points, but up and down. A riddle of burrows created by denizens of the plane - a kind of infinite cave network inhabited by races of elemental being which those of us on the prime material plane do not even suspect to exist. Entire kingdoms carved from solid rock.

From page 177:

The faerie inhabit the air and clouds. Faeries are close relatives of the demihumans, with features of each race: They appear as halfling-sized humanoids with gossamer wings, dwarvish noses and beards, and elvish ears and eyes. Faeries' bodies are light and they fly with little effort. They build their homes of "clouds," and enjoy basking in the sun while storms rage below. They have their own great empire of the wind far above the earth, commonly known only to themselves and a few air creatures.

Like Gene Wolfe's 'Skai', the realm above Mythgarthr, inhabited by overcyns to which mankind owes fealty. A world that exists in the sky and yet also somehow above it, impossible to get to except for blessed individuals or those selected for some special mission - and those who try to reach it are doomed to fall, Icarus-like, into the sea while a boat sails calmly on.

From page 184:

Headsmen (also called "executioners") are NPC humans commonly employed by dominion rulers. They are trained in the business of killing criminals who have received the death penalty. Most headsmen are skilled in the proper use of bladed weapons, ropes, and poisons and are able to execute criminals quickly and neatly.  

All professional headsmen belong to their own guild, which is associated with the Thieves' Guild. Headsmen keep their true identities completely secret, wearing hoods or disguises when engaged in professional activities. Many own ordinary shops, and can seem to be perfectly ordinary townsfolk. Headsmen of 6 HD or more are 90% undetectable in their disguises, and study languages of all sorts to improve their masquerades. Headsmen of 10 HD or more can even use the secret languages of other alignments.  

Thugs: A secret organization exists within the Guild of Headsmen. These evil headsmen enjoy their work too much, and offer their services for open hire. Others call them Assassins or Thugs; they call themselves Pragmati ("the practical people").  

Unlike the Thieves' Guild, the Pragmati are not supported by adventurers or rulers. They are sometimes hired by other NPCs, especially evil ones. However, PCs do not normally contact these headsmen for any reason; their organization is dangerous as either an enemy or an ally. Thugs are treacherous and self-serving, known to extort money from their previous "clients" with threats of exposure, kidnapping, or even murder.

An entire secret realm existing behind and within human society: the Practical People. With its own rulers, its own codes of behaviour, its own rituals, religions and mores. Like the unseelie court - the dark conscience of the natural order of things. A conspiracy of hate and alienation which commits criminal acts at random, leaving those in 'real' society mystified. Yet sometimes, when a cart has just crushed the leg of an unfortunate child, or a hitherto placid horse has bitten the face of its groom, or a building has burned with everyone in it, somebody nearby recognises somebody they know - and yet doesn't Ned have green eyes, rather than blue?