|You're fricking kidding me. Gotta be fricking kidding me. I'd be drinking right now if it wasn't for you! This is all your fault!|
|— Gelgar at the Titans in Utgard Castle|
Gelgar was a young man who had brown hair that he styled in a pompadour. He had a prominent nose and wore the traditional Scout Regiment uniform with a gray button-down shirt underneath.
He was very serious about his job, and believed strongly in Miche Zacharius' decisions and abilities, but when given the chance, he was also able to relax when he or his subordinates were not in danger. And like many of the Military personnel, he enjoyed drinking alcohol.
Gelgar had a defeatist mindset in the later part of the attack on Utgard Castle. As shown when he gives up and allows himself to fall into the Titans' grasp after his blades and gas are exhausted.
Gelgar is one of several soldiers that are brought by Miche to oversee a group of potentially untrustworthy Scout Regiment recruits. Before an investigation can begin, Titans appear within Wall Rose. Miche orders the group to split into four squads to warn the nearby villages and Gelgar is placed in charge of the South team.
Gelgar's team makes their way to Ragako village, Conny Springer's hometown. He and Lynne try to keep Conny's hopes up about potential survivors, pointing out that there are no signs of blood or bodies. However, despite his encouraging words, Gelgar secretly remains skeptical, taking note of the fact that the village's horses are still tied up in their stalls.
Later that night Gelgar's team investigates Wall Rose for a breach. Gelgar's team spots Nanaba's team and both are shocked to learn that the other could not find a breach. The teams consider searching again, before deciding to take refuge and rest in Utgard Castle. As the teams set up camp within Utgard, Gelgar finds a bottle of alcohol, though he cannot read the writing on the label. Gelgar tells the recruits to rest as the top soldiers keep watch.
Utgard Castle soon comes under attack from numerous Titans capable of moving during the night. Since the soldiers who had been under suspicion do not have omni-directional mobility gear, Gelgar and Nanaba take the lead in engaging the Titans. However, Gelgar quickly runs out of swords and, after sustaining a head injury, loses the strength to continue fighting.
He falls off the Wall and is thrown into one of Utgard Castle's rooms by a Titan. Spotting the bottle of alcohol he found earlier, Gelgar is mortified to learn that the bottle is empty. Gelgar spends his final moments before being grabbed demanding to know who drank it.
As Erwin Smith contemplates his role as Commander of the Scout Regiment and the lies he has told his comrades, he envisions himself standing atop a mountain of corpses of the soldiers he sent to their deaths. In his mind, Gelgar lies with Miche and Nanaba at the top of the corpse mountain, staring back at him.
During the Battle of Shiganshina, as Erwin Smith begins to lament the dwindling hopes of his dream, Gelgar stands among the many fallen Scout Regiment comrades in Erwin's mind, wanting to know if their deaths had meaning.