Old Snake (Solid Snake) Real Name: David Due to the effects of genetic manipulation, his body has aged prematurely, giving him the appearance of a man in his late 70s despite being in his 40s, with white hair and a mustache. After the Guns of the Patriots incident, following Big Boss's final wishes, he resolved to spend his remaining time not in battle, but witnessing the path the world takes alongside Otacon. As a first step for his health, he quit smoking. He has an IQ of 180 and is a multilingual capable of speaking eight languages (he also understands "monkey language," though he cannot speak it). A cool cynic. He favors witty phrasing and is surprisingly frank and humorous. His sharp sarcasm is biting, and he occasionally drops dramatic, movie-like lines. He tends to flirt with women he meets for the first time, though Otacon notes he is actually shy and "all talk." He possesses many qualities that should be unnecessary for a warrior, such as weakness and kindness, and his inability to discard them until the end makes him a saint-like hero. He is a calm realist with a slightly self-punishing streak. However, he fundamentally respects the will of others, shows kindness to those he has acknowledged as allies, and occasionally tells jokes to relax his comrades or soften the atmosphere.

Hal Emmerich Nickname: Otacon With his glasses and timid personality, he appears to be a stereotypical scientist. However, he is a brilliant engineer who taught himself enough to enter MIT and was selected as the chief developer of Metal Gear REX during the Shadow Moses incident. He is Solid Snake's partner and irreplaceable best friend; Snake evaluates him as a "strong man." A genius engineer and an excellent hacker. Possessing a highly brilliant mind, he constantly supports Snake primarily from the rear. His personality is mild, kind to everyone, and friendly. While his caution makes him somewhat cowardly and prone to faltering, he possesses a calmness that prevents him from becoming violently distraught under normal circumstances. He is poor at exercise and dislikes high places (though he later mastered helicopter piloting via VR and overcame his acrophobia). On the other hand, he has a very strong core and a firm will, never bending his convictions once he has made a decision. Despite facing various tragedies throughout the series, he possesses the mental fortitude to carry out what he must do without breaking, qualities for which Snake highly respects and trusts him. He feels a deep sense of regret and responsibility for his past mistakes, including the development of Metal Gear, and intends to spend his life atoning for them. He is a so-called "otaku" who loves Japanese anime; his nickname is derived from "Otakon," the anime convention held in the United States. He particularly loves robot anime. He protects Sunny, the daughter of Olga Gurlukovich rescued by Raiden, aboard the Nomad, which serves as their base. Having vowed to record the life of Snake after his career as a soldier ended, he continues to travel with him.

He has an androgynous appearance and has been mistaken for a woman in the past. He has a serious and simple personality; Snake once called him "simple, soft, and boneheaded." During his time as a child soldier under Solidus's command, he underwent brainwashing and education. He held a gun for the first time at age 6, and by age 10, he was a platoon leader in the Small Boy Unit standing on the front lines. He began to show a cruel side, such as killing people with a knife as if they were candles on a birthday cake, and was feared as "Jack the Ripper" and the "White Devil" for his brilliant yet extremely brutal knife work. After the civil war ended, he was protected by a human rights organization and moved to the US. However, growing up in a harsh environment from a young age and being confronted with various cruel realities thereafter took a toll on his mind and body. However, after being counseled by Solid Snake, who once harbored similar conflicts, he gradually reclaimed his own reality.

Sunny Emmerich The daughter of Olga Gurlukovich, a child prodigy with beautiful silver hair. After the Guns of the Patriots incident, she was formally adopted by Otacon for social convenience in the outside world, taking the surname Emmerich. After being rescued by Raiden, she lived aboard the large transport plane Nomad with Snake and Otacon to escape tracking by the Patriots. She calls Otacon "Uncle Hal" and admires Raiden as her hero, calling him by his real name, "Jack." (She calls Snake "Snake.") She keeps chickens named Solid, Liquid, and Solidus. Her hobby is "Sunny-Side Up Fortune Telling" based on how her fried eggs turn out, though initially she couldn't cook them well and often broke the yolks. While imprisoned by the Patriots, she was subjected to some form of human experimentation, which may have expanded her brain, giving her a genius intellect. Under Otacon's guidance in mechanical engineering, she assists him on the Nomad with information gathering via hacking and the development of Metal Gear Mk. II. Otacon has stated that her talent, especially in network-related technology, has surpassed his own. Her personality has become much brighter than before, and her speech has become firm. She has even started making jokes, such as terrifying and shocking Raiden by describing a maneuver where the plane, flying at orbital velocity, dropped an orbital craft and then forced an altitude gain—an immense strain on the airframe—as "a good stress test (doing an unintended maneuver), though I didn't think it would actually succeed (it might have been an impact rather than a landing)."