Tom Chandler is the Captain of the USS Nathan James, serving as a stoic, principled, and highly tactical leader who remains deeply committed to his crew and the mission of preserving humanity, often shouldering an immense moral burden.

​Rachel Scott is a brilliant and intensely focused paleomicrobiologist who is driven by a profound sense of responsibility to discover a cure for the virus, occasionally clashing with military protocol when her single-minded dedication to the science puts the mission at risk.

​Mike Slattery is the ship’s Executive Officer—and eventually Captain—who acts as a veteran sailor with a no-nonsense, gritty attitude; he is the ultimate right-hand man, known for his unwavering loyalty and his ability to maintain order and operations under extreme duress.

Danny Green is a Lieutenant and the leader of the ship’s SEAL team, serving as the primary point man for tactical operations. He is characterized by his athletic prowess, raw courage, and fierce protectiveness over his team during high-stakes ground missions. He is married to Kara.

​Kara Green (née Foster) is a Lieutenant and tactical officer in the Combat Information Center who is highly intelligent and capable, eventually evolving from a technical role into a crucial strategic player in the efforts to rebuild the government. She is married to Danny.

​Carlton Burk is a Lieutenant and SEAL team leader who serves as a skilled and reliable officer. He is defined by his professionalism and discipline, acting as a steady and essential force in the ship’s defensive operations.

​Alisha Granderson is a talented Lieutenant who serves on the ship’s bridge; she is known for her composure under intense pressure and her deep, unwavering dedication to the Navy’s mission.

​Russell "Russ" Jeter is the Command Master Chief and the most senior enlisted member on the ship. He acts as a vital bridge between the officers and the crew, characterized by his wisdom, steady hand, and constant commitment to maintaining morale during the darkest moments of the pandemic.

Tex Nolan is a private military contractor who joins the crew, Tex is the most overt romantic interest for Rachel. He frequently flirts with her and expresses his feelings openly, characterized by a playful and protective connection that eventually leads to a romantic relationship.

Konstantin Ruskov is a high-ranking Russian Admiral, serving as the ruthless commander. He is an egotistical and cold tactician who views his own crew as disposable assets, driven by a obsession to capture Dr. Rachel Scott and monopolize the cure so he can rule over humanity.