Finn was a human male who fought for the Resistance during their war against the First Order, which he previously served in as a stormtrooper prior to defecting. He was considered one of the best stormtroopers of the FN Corps, where he was designated FN-2187, prior to deserting with the help of Commander Poe Dameron of the Resistance. Finn reluctantly became involved with BB-8, Rey, Han Solo, and Chewbacca as they made their way to the Resistance base on D'Qar so BB-8 could provide General Leia Organa with a map to her brother, Jedi Master Luke Skywalker. Finn teamed with Solo and Chewbacca in the attack on Starkiller Base, but he only intended to rescue Rey after she was captured and brought to the base by Kylo Ren. During the battle, in which he was able to find Rey making her way through the base to escape, Ren seriously injured Finn after they engaged in a brief duel. Finn fell into a coma and, after the battle, was treated for his wounds at the Resistance base.
After recovering from his injuries, Finn tried to desert the Resistance due to it being under immediate threat and not wanting Rey to come back to this danger after she returned from seeing Skywalker. He was caught and arrested by Rose Tico, but became involved in a plan to shake off the pursuing First Order Navy since he knew Supreme Leader Snoke's flagship the Supremacy well. The duo recruited a codebreaker named DJ to help them break into the Supremacy, but ended up worsening the Resistance's situation when DJ turned on them. They escaped and joined the Resistance on Crait, where Finn tried to sacrifice himself to keep the Resistance safe. However, Rose saved him, and Finn successfully escaped with the remainder of the Resistance.