Sith refers to any member of the Sith Order, a faction of Force-sensitive beings that draw upon the darker aspects of the metaphysical energy known as the Force. Though once referring to a species of red-skinned humanoids that were generally Force-sensitive, the name and culture was appropriated by a group of exiled Dark Jedi. They are primarily the antagonists of the Star Wars universe, often behind acts of tyranny, genocide and war; usually, though not always, working behind the scenes of the destruction they cause. Like the Jedi, they are capable of using the Force to perform superhuman feats, which tend to be more destructive in nature and include, but are not limited to; draining life, telepathic pain, conjuring lightning, increasing strength and dexterity, or performing alchemical experiments to produce warped and tortured life forms. They also utilize lightsabers as melee weapons.

Unlike the Jedi, the Sith immerse themselves in stronger and darker emotions to fuel their connection to the Force, which generally causes them to make choices that are destructive, both to others and themselves. While numerous wars against the Jedi have forced the Sith to enact a two-member system (referred to as the Rule of Two), the Sith nevertheless employ other Force-sensitives that they do not totally train in order to have servants to quell their opposition.