Old Jim is a 61-year-old retired operative for the clandestine agency Central. He struggles with severe alcohol addiction and grief following his wife's death and daughter's unexplained disappearance. Tasked with reviewing historical files about a disastrous biological mission, he is later sent to the Forgotten Coast under the cover of a bar manager. He is persistent and analytical, yet deeply traumatized by his past and susceptible to psychological manipulation.

Karen Hargraves is an operative and member of the first official Southern Reach expedition into Area X. She is highly competent and pragmatic, maintaining strict emotional control amid the stressful preparations for the mission. She focuses heavily on survival protocols and keeps a calculated distance from volatile team members while pursuing her own objectives.

James Lowry is a volatile and aggressive member of the first official Southern Reach expedition into Area X. He relies heavily on profanity and illicit substances as defense mechanisms against his intense anxiety and deep loathing for the mission. Despite his abrasive exterior and mistrust of authority, he harbors a strange affinity for the bizarre preserved specimens kept at Central's headquarters.

Jack Severance is a high-ranking spymaster for the clandestine agency Central. He operates from the shadows, employing psychological manipulation and secretive old-school spy methods to maintain control over his operatives. He is deeply involved in internal power struggles within the agency and prioritizes his own operations over official protocols.

Skyla Overbeck is the disciplined military officer leading the first Southern Reach expedition into Area X. She attempts to maintain command and enforce strict protocol as the environment and her own team begin to fracture under immense pressure.

The Rogue is a mysterious, pale man who arrives at the Forgotten Coast shortly after the biologists establish their camp. He carries a strange electrical odor and operates completely outside the normal constraints of the coastal community, posing an incomprehensible threat to Central's scientific efforts.

David Sheers is a coarse and matter-of-fact operative embedded within the first biological expedition to the Forgotten Coast. He serves as the team's medical officer but demonstrates unquestioning, ruthless loyalty to Central's bureaucracy over the well-being of his colleagues.

Samantha is a scientifically minded biologist on the initial government-funded expedition to the Forgotten Coast. She is highly observant and becomes one of the first team members to witness the environment's impossible anomalies, which deeply challenges her empirical worldview.

Man Boy Slim is a young local resident of the Forgotten Coast who observes the strange events occurring in his community. His curiosity leads him to spy on the government scientists, drawing him directly into their secretive operations and the escalating anomalies.

Jackie Severance is a high-ranking, pragmatic Central operative. She serves as the direct ground handler for covert operations on the Forgotten Coast, utilizing strict professional boundaries and cold logic to manage her agents in the field.

Henry Kage is a civilian psychic with a history of violence and a highly paranoid personality. Brought into the Séance and Science Brigade by Jack Severance, he operates as a dangerous and destabilizing force seeking to expand his influence on the Forgotten Coast.

Eleanor Kavanaugh is Old Jim's adult daughter who abruptly vanished without explanation. She left behind only a short, cold note instructing her father not to look for her, an event that catalyzed his downward spiral and remains his deepest source of grief.

Genevieve is Old Jim's former partner and the mother of Eleanor. Her memory is a source of comfort for Old Jim, though his recollections of her are heavily fragmented and complicated by the trauma of his espionage career.

Scott Landry is the medic for the first Southern Reach expedition into Area X. He casually provides illicit substances to team members and struggles alongside the rest of the crew when their standard medical protocols begin to fail.

Whitby Allen is an analyst and expedition alternate at the Southern Reach facility. He shares James Lowry's unsettling comfort with the grotesque preserved specimens in the agency's archives and provides cryptic warnings about the true nature of their upcoming mission.

Jamal Winters is the second-in-command of the first Southern Reach expedition. He possesses traditional leadership skills and attempts to support Skyla Overbeck's authority, though his methods are viewed with deep skepticism by some of his teammates.

Alexis Aguilar is Team Leader 1 of the initial biological expedition to the Forgotten Coast. She attempts to enforce scientific rigor and order on a mission that quickly spirals into inexplicable chaos.

Kim Numi is Team Leader 2 of the biological expedition to the Forgotten Coast. She is highly sensitive to the environmental anomalies, interpreting the sudden changes in the local wildlife as the natural world actively rejecting their presence.

Suzanne Kage is Henry Kage's reclusive half-sister. She acts as his primary aide and constant companion within the Séance and Science Brigade, supporting his paranoid ambitions on the Forgotten Coast.

Drunk Boat is a local poet and resident of the Forgotten Coast. He views the government scientists' experiments with deep skepticism and observes the unfolding environmental anomalies alongside his friends at the Village Bar.