PROXY was a prototype holodroid who served as a companion and long time friend of Galen 
Marek and traveled with him on the Rogue Shadow. Despite their friendship, PROXY would routinely try to kill Marek during training as this was his prime directive provided by Darth Vader. PROXY was equipped with advanced hologram technology that, when coupled with its built-in servos, would allow it to change appearance and adopt a wide range of disguises. He could also present messages: he would turn holographically into the sender, and the sender would say the message. Also, when Galen wanted information on an individual, PROXY would turn into that person and access databases to confirm his/her identity. He was also capable of holding his own in lightsaber combat against Marek for a short time.
After many missions, including rounding up the Rebel leaders, PROXY eventually accompanied Galen and Juno under the guise of Bail's adopted daughter, Princess Leia, to the signing of the Corellian Treaty. Darth Vader and Imperial troops ambushed Senators Garm Bel Iblis, Bail Prestor Organa, and Mon Mothma. But Bail managed to have PROXY cut off Leia's image, so that Vader wouldn't know that she was involved. PROXY in a bold move managed to save the lives of Galen and Juno by using his hologram capabilities to disguise himself as Obi-Wan Kenobi. Vader was momentarily distracted by the assault, enough for Galen and Juno to get away. Vader, being immensely superior to PROXY in lightsaber combat destroyed the droid and succeeded in capturing the Senators.
Some time after Galen's death, the deactivated PROXY was recovered from the snow and harsh winds on Corellia by Senator Organa and Juno Eclipse. They were recovering records of the birth of the Alliance, and wanted PROXY because he held the records of the Alliance founder, Galen Marek. PROXY related exactly the events that led Galen down the path of redemption, up until his own deactivation at the hands of Darth Vader. Galen had also left specific standing orders that in the event of his death, ownership of PROXY would pass to Juno. All the while repairing PROXY, the droid recounts about Marek's adventures, up to the point where the Alliance is born and destroyed and when he sacrifices his life to save Marek. Juno then tells him how Marek went valiantly to save Kota and the Senators' lives and sacrificed himself so they could escape. As they arrived on Kashyyyk, PROXY said that since Vader and Palpatine had survived, his master's death was meaningless. Bail, however, said it made all the difference to him and the other rebels, since his sacrifice had saved them.
Over the course of his activation, PROXY held within him a number of combat stances and fighting skills from various fighters which included:
-Obi-Wan Kenobi
-Anakin Skywalker
-Qui-Gon Jinn
-Rahm Kota
-Maris Brood
-Shaak Ti
-Emperor's Shadow Guard
-Darth Maul
-Juno Eclipse
Full Synopsis: http://starwars.wikia.com/wiki/PROXY
