Derek Wildstar serves as tactical commander aboard the space battleship Argo. Hailing from Earth, he suffers profound family loss early on when alien planetary bombardment kills his parents. His brother, Alex Wildstar, apparently dies during a battle over Pluto while covering Captain Avatar's retreat, leaving Derek without immediate family. This loss ignites his deep resentment toward Avatar, whom he blames for Alex's death.

Derek matures from a hot-headed officer into a responsible leader during the voyage to Iscandar. He reconciles with Avatar and shoulders increasing responsibilities, eventually becoming deputy captain as Avatar's health fails. After Earth's ecological restoration, Derek faces new threats as acting captain and Star Force commander during the Comet Empire conflict. He commands the Argo against Emperor Zordar's forces, intent on conquering Earth rather than colonization. Despite former Gamilon leader Desslok aligning with Zordar against Earth, Derek coordinates defenses with the Earth Defense Force.

His personal life evolves alongside command duties. A romantic relationship develops with Nova Forrester, the Argo's radar operator and nurse, providing a stabilizing influence during extended conflicts. Later, confronting a crisis where Earth's sun faces thermonuclear destruction, Derek assumes full captaincy of the Argo. He spearheads the search for a new homeworld for humanity while navigating hostilities between the Galman and Bolar civilizations.

Post-missions reveal further developments. Retiring from military service, Derek joins the merchant fleet and starts a family, though prolonged absences strain the relationship. He is later recalled to command during emergencies, such as his partner's ship vanishing. A significant revelation occurs when Alex Wildstar emerges alive on Titan after his ship's crash-landing, altering Derek's understanding of past events. His leadership style increasingly reflects Avatar's influence, emphasizing tactical ingenuity and independent decision-making.