Luke Skywalker is a character from the Star Wars franchise, a Jedi Master in the New Jedi Order, and a friend of Kyle Katarn and Mara Jade.
Besides being a skin available in the multiplayer mode for Mysteries of the Sith, the only participation of Luke Skywalker in the actual games is the secret mission on the Mysteries of the Sith CD-ROM, which is a recreation of the mission to Cloud City.