4. By the evil of my actions a new plane was formed: the Demiplane of Dread. Imprisoned within its borders, I now rule the domain Barovia from Castle Ravenloft.
Who am I?
From Quiz Ambassadors of Despair
Answer:
Strahd von Zarovich
In the beginning Strahd von Zarovich was a successful field general who was respected for his strategic genius and his prowess with the sword. Although it was never made clear which plane he called home, we know that one of his homeland's rituals was the 'Land's Bonding', in which Strahd would let his blood drop onto the ground while announcing "I am Strahd. I am the land. I, Strahd, am the land." - thusly creating a mystical connection between land and ruler.
Shortly after conquering Barovia and ruling his new land from Castle Ravenloft, Strahd fell into a deep depression, nurtured by his jealousy towards his younger brother Sergei's youth, and the beginning fear of his own mortality.
It was during that bleak personal crisis that Strahd fell in love with a young beauty called Tatyana. This affection, however, was not mutual; instead, Tatyana became engaged to Strahd's brother Sergei.
Driven by deep jealousy, Strahd decided to accept a pact with death itself, granting him life and youth eternal. On the night of Sergei's and Tatyana's wedding, he killed his younger brother and tried to win his beloved's heart. To no avail: Tatyana flung herself from Castle Ravenloft's battlements and died on the rocks beneath the old fortress.
Strahd von Zarovich was then shot and fell into darkness while the Mists of Ravenloft closed in around him. When he arose from the dead, these Mists had already sealed shut the realm, and Strahd von Zarovich had turned into Barovia's vampiric ruler.
Apart from the usual rule and source books, the story of Strahd von Zarovich can be read in P. N. Elrod's novels 'I, Strahd - The Memoirs of a Vampire' (1993) and 'I, Strahd - The War Against Azalin' (1998). The Devil Strahd is also featured in James Lowder's 'Knight of the Black Rose' (1991).