The aboleth is a fantastic creature, not merely for its powers and abilities, but for the myriad of uses one can find for these strange beasts.
If you have never heard of an author named H.P. Lovecraft, I would highly recommend you find out more about him if you wish to bring an element of horror and dread to your RPG table. Particularly a short story called The Call of Cthulhu. The story, written in first person, tells the tale of a man driven to the bring of insanity by a horror he has witnessed, and a terrible truth he has learned.
Now, the aboleth is a horrifying creature that can really be used to great effect to terrify low-to-mid level characters. Other variations can be found to use at higher levels, making them fantastic villains to plague players for an entire campaign. They are aquatic, preferring to live deep within underground lakes and rivers. Perhaps most frightening of all, they have the ability to dominate the minds of others, controlling them and turning them into their slaves. Entire communities have been infiltrated by aboleth slaves, and before one knows it, the town is under their control. They wield powerful illusionary magic. They are older than the stars and cannot die unless killed. Combined, one could not ask for better qualities in a campaign villain.
As the adventure got deeper and more ominous, I decided to make the aboleths come from a place called the Far Realm, or the Dark Tapestry. Already a place influenced by Lovecraft's work, this realm was a place of madness, located far beyond the stars and beyond the knowing of any sane man. It fit perfectly into the Lovecraftian feeling I was attempting to convey. To this day, in almost all campaigns I run, aberrations are from a place beyond madness. A place that man was not meant to know. They are the way that I like to bring a Cthulhu theme to my games, something to make the players despair and feel no hope. I am quite proud of my first reveal of an aboleth, coming out of a black portal, inky water spewing out, its eel-like slithering body oozing out of the portal and sliding across the floor. The players, weakened and frightened at the horrors they had already witnessed in the town, ran for their lives and their sanity. An adventure well-concluded.
If you are a fan of the dark and macabre, I would suggest taking a look at aberrations in a new light. Not as ugly beasts meant to be killed in a night of hack-and-slash, but as otherworldly aliens that can be used to eerie effect, to frighten your players and make them respect the dangers of insanity. Looking at enemy types in new ways is a feature I hope to bring to The Adventurer's Tomb often. Stay tuned tomorrow for "B is for Boss".
D&D 3.5 Aboleth