The Brotherhood of Bluebeards is an old, illegal group consisting of wealthy bachelor unicorn stallions identified by their manes and facial hair (dyed blue) and a pin showing the sigil of their organization- a key and a knife.

Originating in Cheval, members of the Brotherhood of Bluebeards are murderers with a distinctive M.O.

First, they find unmarried mares and take them as brides. After a period lasting anywhere from a few days to a month, the stallion will announce that he is leaving for a trip to the country, and give the keys for the various rooms in his mansion to his current wife. She is able to open any door in the house with them, each of which contain some of his riches, except for an underground chamber that he strictly forbids her to enter, lest she suffer his wrath. He then goes away and leaves the house and the keys in her hooves.

Eventually, the wife will usually end up opening the door to the underground chamber, discovering the Bluebeard's larder- a room filled with blood and the murdered corpses of the Bluebeard's former wives hanging on hooks from the walls.

The key to this room is always enchanted to appear bloodstained if anyone besides the Bluebeard opens the door, meaning that there is evidence when the stallion returns- always the day immediately after his wife opens the chamber. The stallion will then kill his wife, and continue the cycle until found out. Occasionally, certain members prefer to extend the "game", giving their brides a 10 minute head start to begin running before the Bluebeard hunts them down, but some other members of the Brotherhood see this as unnecessary and extreme.

Members of the Brotherhood can be surprisingly difficult to track down, though so far more than 100 have been brought to justice over the past 2 centuries.