Mars Sapientia is a minor character in Final Fantasy XV: Episode Ardyn. He is a member of the Insomnian border patrol who reported to duty at his appointed time, but went MIA sometime before dawn on Founder's Day, M.E. 734. He was daemonified by Ardyn Izunia, who took on his appearance to sneak into Insomnia. Having read Mars's memories, Ardyn could perfect his disguise to such extent not even his best friends would be able to tell.
Mars's MIA status is reported on the radio in a broadcast otherwise dedicated to the heightening of Lucian-Niflheimian animosity, as well as the Founder King's Day celebrations. When dropped off at Insomnia, the taxi driver asks Ardyn if he was to look for Mars Sapientia as well. Ardyn declines, claiming he is on "special assignment."
Mars is a 28-year-old, tall, fair-skinned man with short dirty blond hair and blue eyes. He was last seen wearing his border patrol fatigues. Mars's attire is the same the border patrol guards wear in Kingsglaive: Final Fantasy XV. The scene where Ardyn enters Insomnia under Mars's guise is a recreation of an old Final Fantasy Versus XIII trailer where Noctis Lucis Caelum entered Insomnia in a black car.
Sapientia is the Latin word for "wisdom".
Mars Sapientia is thus a fitting alias for Ardyn, whose name may mean "burning", and who was involved in the war and gained the wisdom of Ifrit the Infernian. Mars Sapientia's name is similar to Ignis Scientia, whose name means "fire knowledge" in Latin.