Loumara

The loumara are a relatively new demonic race, much younger than the tanar'ri. They are still centuries old, but this is still recent in a place like the Abyss, where time doesn't mean the same thing it does on the Material Plane. As a result, no loumara has yet become powerful enough to be recognized as a demon lord.

Loumara are usually immaterial or invisible demons that are more like ghosts or undead than demons. All loumara can possess living creatures.

Dybbuk
A Dybbuk resembles a jellyfish with a simply sketched human face. Dybbuks can possess and control dead bodies, so they spend a lot of time looking for a 'perfect' host body to animate – one that died without violence or major injury, and preferably one that is handsome or beautiful. After taking the control of a 'perfect' body, dybbuks try to insert themselves into the society of the victim, plunging into depravity and hedonism until their possessed body is broken down and ruined. When a 'perfect' body is not available, a dybbuk will take a less desirable body and continue to search for a better host. Dybbuks are lonely creatures, and can be found in groups only where there are many corpses to possess, such as on a recent battlefield. They tend to avoid undead, because already-animated bodies are of no use to them.

Guecubu
A Guecubu resembles a mass of vapor, and is born from dreamstuff tainted by evil. Guecubus can possess and control the body of sleeping humanoids. Once they are in control, they 'ride' silently, letting their victim go about his or her business. At some point they take control and lash out, trying to spread death and murder – particularly the victim's family and friends. Sometimes the guecubu will conceal its actions even from the victim, letting them believe that they are cursed or jinxed.

Guecubus believe that killings form some sort of pattern, and enough spilled blood will eventually reveal the meaning of creation in this pattern. They rarely form groups with other guecubus, preferring to remain hidden and anonymous. However, many of them can be found in the Dreaming Gulf (230th layer of the Abyss), where they are created spontaneously from the raw, churning chaos of dreams.