Mark is an American botanist and mechanical engineer on the Ares 3 mission. Left for dead on Mars after an antenna impales him during a severe storm, he relies entirely on his scientific expertise to stay alive. He utilizes his botany background to farm potatoes inside the Mars Lander Habitat and modifies the mission's rovers for long-distance travel. Operating millions of miles from Earth, he utilizes a dark, self-deprecating sense of humor to cope with his extreme isolation.

Melissa commands the Ares 3 mission and pilots the Hermes spacecraft. She bears the heavy guilt of leaving Watney behind, having made the necessary call to abort the mission to save the rest of her team. A fan of 1970s disco music and vintage American television, her digital media collection inadvertently provides Watney with his only entertainment on Mars. She is a firm leader who prioritizes the safety of her team above all else.

Venkat is the director of Mars operations for NASA, overseeing the Ares 3 mission from Earth. He bridges the gap between scientific problem-solving and bureaucratic administration, frequently advocating for direct action. Deeply concerned about Watney's welfare, he actively collaborates with the Jet Propulsion Laboratory to establish communication and devise rescue strategies.

Teddy is the head of NASA, responsible for the organization's public image and the safety of all its astronauts. He frequently faces difficult bureaucratic decisions, balancing the desperate need to help Watney against the political and physical risks to the agency and the rest of the Hermes crew.

Rick is the pilot for the Ares 3 mission and serves as the primary source of humor among the Hermes crew. He shares a close friendship with Watney, who considers him his best friend. His wooden religious cross, left behind on Mars, inadvertently provides Watney with the means to start a crucial fire.

Beth is the software engineer for the Ares 3 mission. Her coding skills prove essential for operating the Hermes spacecraft and processing complex data. As the smallest member of the crew, her physical size plays a role in the crew's emergency contingency plans.

Chris is the in-flight surgeon and Extra-Vehicular Activity expert for the Ares 3 crew. He is responsible for external spacecraft operations, spacewalks, and monitoring the physical health of the astronauts during their long deployment.

Alex is the chemist aboard the Ares 3 mission. His scientific expertise provides critical utility when the Hermes crew faces high-stakes mechanical and chemical problems during their extended flight.

Mitch is the flight director for the Ares 3 mission. He acts as a fierce advocate for the Hermes crew and consistently pushes back against administrative caution. He prioritizes the immediate well-being of the astronauts over NASA's public relations concerns.

Annie is the director of NASA media relations. She manages the unrelenting global news coverage and press conferences surrounding Watney's predicament. She fields difficult questions from reporters and shapes the public perception of the rescue efforts.

Rich is a physicist at NASA specializing in orbital mathematics. He focuses on calculating complex spacecraft trajectories and develops an unconventional orbital maneuver designed to alter the flight path of the Hermes.

Mindy is a satellite communications officer at NASA. She is the first person on Earth to realize Watney is alive after spotting cleaned solar panels and deployed rover tents. She is subsequently promoted to track Watney's daily movements across the Martian surface.

Bruce is the director of the Jet Propulsion Laboratory. He works relentlessly, often sacrificing sleep, to design, test, and modify the equipment and spacecraft necessary to resupply Watney and facilitate his survival.

Dr. Shields is the flight psychologist for the Ares missions. She provides public insight into Watney's cheerful, resourceful temperament and explains why his personality makes him uniquely suited to endure extreme isolation.

Zhu Tao is the underdirector of the China National Space Administration. He recognizes that a Chinese booster probe could reach Mars and suggests an international collaboration to assist in the resupply effort.

Guo Ming is the director of the China National Space Administration. He negotiates offering Chinese space technology to NASA in exchange for placing a Chinese astronaut on a future Ares mission, providing critical hardware for the rescue.