The Ninja Edit
Ninjas are mystical warriors who rely on stealth and surprise to make short work of their enemies. While a ninja can be a deadly foe they lack some of the lasting power of more robust warrior types such as fighters and barbarians but make up for this with their impressive skills and unique abilities. Ninjas power their more exotic and magical abilities through a form of energy known as Ki, a source of power which ninjas claim comes from within rather than from arcane magic or granted by the divine.
Ninjas in Eberron Edit
Most ninjas in Eberron can trace their heritage back to the elven families gifted with the Mark of Shadow and though it has spread beyond the house and it's associates all major ninja schools can be connected to House Phiarlan in some way. Ninja are now used across Khorvaire as spies and assassins and the ninja way of life is popular among elves (most still related to House Phiarlan), halflings who live within large cities as well as with Changelings.
The only notable ninja tradition outside of those once or still associated with House Phiarlan are a group of shaarrat'kesh goblins who claim that their ninjas came first, dating their warriors back as far as the Dhakaani Empire.