X-12
in the revised rough draft of Star Wars: Episode I - The Phantom Menace, this destroyer droid accompanied P-59 to attack the Jedi Knights who came aboard the Trade Federation command ship to negotiate the blockade of Utapau. (IG1)

XP-21
an outdated personal grooming device. (SWH)

XP-36
Kenner Toys proposed the production of this speeder toy, a high-performance, lightly-armed vehicle, as part of its 1986 line of Star Wars toys. (SWG2)