X9 is the villain protagonist in the Samurai Jack Episode Tale of X9. He is an assassin droid who worked for Aku but later came out of retirement.
X9 was created as one of Aku's early robots by the some of his scientist. X9 was given an artificial emotion chip by one of the scientists that makes him feel emotions. This also made X9 think on his own and made him to live on. He managed to survive through obstacles and helped Aku conquer the world where other droids failed. X9 later went into retirement and took in a stray dog named Lulu
Years later, X9 was came out of retirement by Aku who kidnapped Lulu. He demanded that X9 kill Samurai Jack or Lulu dies. X9 finds Jack and follows him to a an abandoned droid factory. Jack destroys X9 and showed sympathy to the droid. X9 in final words begs Jack to take care of Lulu.
- X9 was voiced by Darran Norris.