A deserter was an individual who decided to leave military service without permission, often due to disillusionment with said military.
Cut Lawquane was a clone trooper who deserted the Grand Army of the Republic during the Clone Wars when his transport was attacked by Separatist gunships, leaving his fellow soldiers either dead or injured. The Sullustan Bokk Naarg attempted to desert the late Saw Gerrera's partisans to Imperial custody, alongside Pantoran Sharima, in exchange for information, claiming he had realized the futility of their cause. Finn was a notable First Order military deserter who defected after becoming disillusioned during a combat assignment on Jakku, deciding he didn't want to fight for the First Order's ideals. Though he originally planned to start a new life away from the First Order, he soon found himself in service with the Resistance.