X1 was a Force-sensitive clone trooper who served the Galactic Republic and later the Galactic Empire. Along with his brother, X2, he was created by the Kaminoans from the DNA of a Jedi Knight, Falon Grey, and grew up in secret on the planet Kamino. Following the outbreak of the Clone Wars in 22 BBY, X1 and his brother joined the Grand Army of the Republic and fought in many battles of the war, helping to train young clone troopers under the eye of Jedi Master Ferroda. During a battle on the planet Cato Neimoidia, however, Order 66 was enacted, and X1 and his brother were forced to kill Ferroda.