3/4" tall.
The Sith Order
was a sect of Force-sensitives who utilized the dark side of the Force. The term "Sith" originally referred to a species of aliensnative to the planets Korriban and Ziost, who were later enslaved and ruled by exiled Dark Jedi from the Galactic Republic. These Dark Jedi had once been members of the Jedi Order, a monastic Force religion dedicated to peace through the use of the light side of the Force. The Dark Jedi, who refused to rely exclusively on the light side, challenged the Jedi by giving in to the dark side, which started the Hundred-Year Darkness.
From, http://starwars.wikia.com