Barovia is the name shared by a number of distinct but related locations within the fictional universe of the Dungeons & Dragons roleplaying game. In each of its iterations, the area is loosely based on real-world Transylvania and its associations with the Dracula legend.
Barovia first appeared as the setting of I6: Ravenloft. Later, TSR developed this original adventure into the Ravenloft campaign setting, and writers reconceived of Barovia as one of many domains within the Ravenloft demiplane.
Barovia is a mountain valley within the fictional Balinok mountains. The terrain is densely wooded and the climate is one of frigid winters.
The valley hosts a small village (also named Barovia), over which looms Castle Ravenloft, ancestral seat of vampire ruler Strahd von Zarovich.
As originally conceived of in I6: Ravenloft, the history of Barovia mirrors the story of Dracula.
Barovia was conquered in the year 347 of Barovia's calendar by Strahd von Zarovich.
Sometime around 351, as detailed in I, Strahd: The Memoirs of a Vampire; a novel published by TSR in 1993 details Strahd's transformation to vampire as a deal gone wrong with a personification of Death itself in an attempt to win Tatyana's love away from his brother.
I6: Ravenloft: The setting's original appearance, for 1st edition AD&D.
House of Strahd: Largely the same setting as I6, but updated for 2d Edition AD&D.
Expedition to Castle Ravenloft: An update and expansion to the adventure, for the 3.5 edition of D&D. Includes instructions for incorporating Barovia into the Eberron and Forgotten Realms campaign settings.