Mattis Banz was a male human who served as a member of J-Squadron, a training unit within the Resistance fighting against the First Order. Born on the agricultural planet of Durkteel circa 19 ABY, Banz was raised as an orphan, under the care of a Phirmist temple; there, he listened to stories of the Rebellion that defeated the Galactic Empire. During this time, he cultivated a heroic nature, aspiring to emulate figures like Luke Skywalker, Leia Organa, and Admiral Gial Ackbar, frequently assisting younger orphans in need.
In 33 ABY, Resistance recruiter Antha Mont took notice of Banz's actions, leading the orphan to join the Resistance and train as a pilot within J-Squadron, a group of cadets. One month after his arrival at the Resistance base on D'Qar, Banz and some other J-Squadron members were responsible for an accident that almost caused the deaths of several starfighter pilots. As a consequence, Admiral Ackbar dispatched them on a scavenging mission to Vodran. However, while they were on Vodran, Banz and his group encountered stormtroopers from the First Order and were captured.