A lidérc () is a unique supernatural being of Hungarian folklore. It has three known varieties, which often borrow traits from one another.
The first, more traditional form of the lidérc is as a miracle chicken, csodacsirke in Hungarian, which hatches from the first egg of a black hen kept warm under the arm of a human. Some versions of the legend say that an unusually tiny black hen's egg, or any egg at all, may become a lidérc, or that the egg must be hatched by placing it in a heap of manure.
The lidérc attaches itself to people to become their lover. If the owner is a woman, the being shifts into a man, but instead of pleasuring the woman, it fondles her, sits on her body, and sometimes sucks her blood, making her weak and sick after a time. From this source comes a Hungarian word for nightmare -- lidércnyomás, which literally means "lidérc pressure", from the pressure on the body while the being sits on it. Alternate names for the lidérc are iglic, ihlic in Csallóköz, lüdérc, piritusz in the south, and mit-mitke in the east.