This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Strigoi (Romanian)
Strigoi in Romanian mythology are troubled spirits that are said to have risen from the grave. They are attributed with the abilities to transform into an animal, become invisible, and to gain vitality from the blood of their victims. Bram Stoker's Dracula has become the modern interpretation of the Strigoi through their historic links with vampirism.
The original story came from Ancient Greek and Roman legend of Strix creature, a bird of ill omen which fed on human blood and flesh. They are also known as vampires. Strigoi or vampires are considered lethargic and drowsy during day and active during the night. They attack their victims during the night leaving teeth marks on the corpses.