X-10, alternatively referred to as Ex-Ten, served as a droid within the Nihil, a marauder group, throughout the High Republic Era. This occurred during the time when Eye of the Nihil Marchion Ro, along with other Nihil members, were based on Quantxi, which is the Junk Moon orbiting Ord Mantell. X-10 stayed on their vessel. When the Nihil members on the moon were assaulted by the local Junk Mavens, Ro commanded the marauder Zagyar to instruct X-10 to prepare their starship for departure.
The comic series Star Wars: The High Republic Adventures, specifically its third issue, marked X-10's initial appearance, although the droid was not identified at that time. This issue was authored by Daniel José Older and released on April 7, 2021. In issue 5, Marchion Ro gives the order for X-10 to get their ship prepared; however, it wasn't certain if X-10 was the same droid previously seen with Zagyar. Later, Older verified on Twitter that the droid accompanying Zagyar was, in fact, X-10, according to the scripts.