I am officially hooked on the new series, The Strain. The vampires are visually interesting, departing from the ongoing trend of the sexy vampire. While beautiful vampires make sense from an evolutionary standpoint (as Z.D. Gladstone pointed out), sometimes it's refreshing to see them portrayed as an effective and hideous predator. Throughout the beginning of the season the word "strigoi" is brought up repeatedly, which prompted some research.
Slavic mythology was the foundation for the modern day vampire, although vampire-like creatures predate hieroglyphics. The Western European vampyr became very popular with Bram Stoker, and his writing relied heavily on Romanian mythology and Vlad II of the House of Drăculești. A super brief history on Vlad the Impaler (for more I recommend the short documentary The Real Count Dracula):
Vlad was a ruthless but very successful strategist. He was known for his cruelty, which may have stemmed from spending a large portion of his youth as a hostage of the Ottoman empire. When Pope Pius II called for a crusade against the Ottoman, Vlad raised his hand and aligned himself with Matthais Corvinus. The Ottoman sent an envoy to demand tribute and Vlad responded by nailing their turbans to their heads and shipping their bodies back. He used surprise attacks and constructed a forest of impaled bodies to intimidate his Ottoman foes. Unfortunately these tactics and his heavy hand as a ruler led to his own people turning against him and death.
Vlad the Impaler was just a man, albeit a man with a horrific mean streak. The legend of the strigoi has also changed over time. As I've mentioned, vampire-like beings are not a new concept. Blood has been viewed as the source of life and consumed going as far back as hieroglyphics. At least. The legends continue to morph as they appear in our writing, graphic novels, movies, and television. Today's story tellers are still perpetuating the original myths.
The strigoi are said to date as far back as the Dacians and are troubled or evil souls. There is a living form (strigoi viu) which are cursed people born with some kind of "sign" (red hair, the seventh sibling born of a single sex, any birth defect, or born with a caul). They may or may not have magical abilities but are buried with caution for fear that they will return as a strigoi mort and risk eternal damnation. The strigoi mort are cursed spirits that have risen from the grave.
In The Strain it is said that the strigoi mort first returns to those it loves most. This is in keeping with the myth, however, the strigoi raises in poltergeist form to make mischief in their family home. After a period of time (7 days in most of the documentation I've found), they can take their original physical form and wreak havoc. Each evening they have to return to their graves. If they are not exhumed, beheaded, and burned within seven years, they are no longer tied to their grave and can travel at will. At this point, their souls are also lost.
Strigoi have the ability to take on animal form, invisibility, and the ability to drain the energy from their victims. This doesn't appear to have been explicitly through blood, although the myth has evolved so that the strigoi mort are now considered immortal vampires. There have been documented cases of strigoi as far back as 1672, but "vampire hysteria" really hit in the Slavic countries in the 1700's and still continues in some regions where people are buried with great caution.
I have a theory that The Strain ninjas who made an appearance in the last episode are actually the moroi, or the Romanian mortal vampire, but that's another topic for another day.