X1 is a Force-sensitive clone trooper created by the Galactic Republic towards the end of the Clone Wars. A clone created with the DNA of a Jedi Master, X1 was assigned to help the Republic in various missions against the CIS. His younger clone brother was X2, created for the same purpose. However, after the battle on Cato Neimoidia and the enacting of Order 66, X2 decided to leave his dark past behind and fight the Galactic Empire, while X1 chose to stay with the Empire.

X1 and his brother met later on Dantooine. X2 helped Falon Grey, the brothers' genetic father, fight Imperial stormtroopers, but X1 arrived, killed Grey, and left X2 to die. X1 helped the Empire in many ways, including at the Battle of Hoth. The brothers were reunited on a Star Destroyer, and after a short battle, the two escaped the exploding ship.

After the Battle of Endor and the death of the Emperor, X1 became a Sith Lord and operated from Darth Vader's fortress on Vjun. X2, now a Jedi Knight, and the forces of the young New Republic infiltrated the fortress only to find that X1 had escaped to Mustafar. However, using a Sith holocron, X2 tracked his evil brother to Mustafar and attacked the planet in a short battle. X1 attacked his brother above the planet and then in his laboratory of insane clones on the fiery surface. X1 confronted his brother one last time, and the Jedi defeated him, sending him burning into the lava.

           Star Wars Legends Villains

Galactic Alliance Guard
Darth Caedus | Tahiri Veila

Galactic Empire
Armand Isard | Baron Merillion Tarko | Carnor Jax | Natasi Daala | Ozzik Sturn | Rom Mohc | Sarkli | Sate Pestage | Trioculus | Ysanne Isard | Faie

One Sith
Leader: Darth Krayt
Sith Lords: Darth Azard | Darth Havok | Darth Luft | Darth Maladi | Darth Nihl | Darth Rauder | Darth Reave | Darth Ruyn | Darth Stryfe | Darth Talon | Darth Wyyrlok I | Darth Wyyrlok II | Darth Wyyrlok III | Darth Vurik | Darth Wredd | Saarai | Vul Isen
Soldiers: Darth Krayt's Sith Troopers | Morlish Veed

Prophets of the Dark Side
Cronal | Darth Millennial | Jedgar | Kadann | Sariss

Sith and Dark Jedi
Abeloth | Ajunta Pall | Aleema Keto | Alema Rar | Azrakel | Brotherhood of Darkness | Dark Apprentice | Dark Underlord | Darth Andeddu | Darth Bane | Darth Cognus | Darth Desolous | Darth Gean | Darth Gravid | Darth Guile | Darth Homiiz | Darth Karnage | Darth Morias | Darth Phobos | Darth Plagueis | Darth Ramage | Darth Rivan | Darth Ruin | Darth Scabrous | Darth Simi | Darth Vectivus | Darth Venamis | Darth Zannah | Desann | Exar Kun | Freedon Nadd | Galen Marek | Jerec | Joruus C'baoth | Kazdan Paratus | Komari Vosa | Lumiya | Luuke Skywalker | Mara Jade | Maris Brood | Reborn | Rugess Nome | Sarcev Quest | Skere Kaan | Tavion Axmis | Ulic Qel-Droma | Unidentified Sith Master (Dxun) | X1 | Xanatos | XoXaan

Yuuzhan Vong
Mezhan Kwaad | Nas Choka | Nen Yim | Nom Anor | Onimi | Peace Brigade | Shimrra Jamaane | Tsavong Lah

Burbakker Teep | Chop'aa Notimo | Drexl Roosh | Durga the Hutt | Gardulla the Elder | Gault Rennow | Gorog | Granta Omega | Groff Haugg | Hanharr | Jenna Zan Arbor | Kleef | Meeko Ghintee | Montross | Prince Xizor | Thrackan Sal-Solo | Zorba the Hutt | Lord Starkiller