Vampire Academy by Richelle Mead

What sets this series apart is its unique vampire hierarchy, heavily inspired by Romanian folklore. The world is divided into three distinct groups:

• The Moroi: Living, mortal vampires. They possess magical elemental powers (Earth, Air, Fire, Water), drink blood but don't kill, and age like humans.

• The Dhampirs: Half-human, half-vampire hybrids. They do not drink blood and have no magic, but they possess incredible human strength and reflexes. They train ruthlessly to become Guardians sworn to protect the Moroi.

• The Strigoi: The villainous, immortal, undead vampires. They are fiercely violent, super-strong, and can only be made if a Moroi intentionally kills someone while feeding, or if a victim is forced to drink Strigoi blood.