Sith assassins was a title held by some assassins who served the Sith Order, specializing in stealth and dealing high amounts of damage to enemies in melee combat. They were known to primarily wield saberstaffs in combat, and some were adept at concealing themselves with the Force.

In Star Wars: Knights of the Old Republic II: The Sith Lords, Sith assassin is one of the six prestige character classes which the main character can select after reaching level 15. Like its light side counterpart, Jedi Watchman, this class corresponds to the Jedi Sentinel non-prestige class. All the in-game Sith assassins have this character class. Jedi Watchman and Sith Assassin, unlike the Jedi Master/Sith Lord and Jedi Weapon Master/Sith Marauder counterparts, are not «one for one» ability trades. Sith Assassin has a lower feat and save progression, but gains more sneak attack dice.

When you enter the Trayus Academy, an assassin appears with two lightsabers; a normal one, and a short-bladed. This is the one of the two elite Sith assassins. An elite Sith assassin appears on Citadel Station wielding a double-bladed lightsaber during the battle of Telos IV in KotOR II.

The Sith Assassins in KotOR II wear masks that have striking aesthetic similarities to the mask worn by Darth Vader (without the helmet).

The Sith Assassin is an advanced class for the Sith Inquisitor class in the Star Wars: The Old Republic MMO video game. This advanced class specializes in the use of the double-bladed lightsaber, stealth, and dealing bursts of damage in battle. They can also be able to tank, using Force Powers and Lightsaber skills to protect allies and members of the Empire and themselves. The Republic counterpart for this archetype is the Jedi Shadow.