Originally introduced in the 1983 module Ravenloft, the vampire Strahd von Zarovich is the villain and ruler of Barovia. He was created by Tracy Hickman (also known for co-creating Dragonlance with Margaret Weis) and Laura Hickman. Ravenloft is also known as the Demiplane of Dread and is a pocket dimension that contains and traps Strahd as punishment for his evil acts and depravity. That begs the question of why his innocent subjects were trapped with him, but that's another issue. The setting was so popular it launched several novels and videogames.
Ravenloft was the first of D&D's classic settings to be revived for 5th Edition, and it was a good choice. Distinct, evocative, and self-contained, Curse of Strahd had a flavor and mood unlike any of the 5th Edition adventures released to that point, or since. While Chris Perkins is the lead designer on CoS, it was created in consultations with the Hickmans, incorporating material they refined in their own games in the decades since its commercial launch.