Dave McCartney is a fictional gunsmith from the long-running series Golgo 13. He resides in New York City, where he operates a hidden workshop located in the basement of the Dave's Funeral Home, using his position as a janitor at the establishment as a cover for his real profession. Physically, he is depicted with a wide forehead, round glasses, and prominent front teeth, often seen working in overalls. In later appearances, his hair is shown with streaks of gray.

As a professional, McCartney is described as one of the top five gunsmiths in the United States, taking great pride in his craftsmanship. His skills cover a vast range of expertise, including internal and external ballistics, metallurgy, and the ability to source rare and specialized components through an extensive network of contacts. He is a genius mechanic capable of designing and building highly unconventional firearms and ammunition from scratch, often under extreme pressure and within impossible time constraints.

Despite his world-class abilities, McCartney has a personality that contrasts sharply with the serious tone of his primary client. He is known for his casual demeanor, complaining about difficult requests, and maintaining a workshop that contains items like adult magazines and televisions, which seems unfitting for a master craftsman. His typical attitude is one of gruff reluctance, frequently grumbling about the troublesome nature of the jobs he is asked to perform, particularly the impossible deadlines. However, when he is focused on a project, his demeanor changes completely, and he becomes solely dedicated to the work at hand.

McCartney's role in the story is almost exclusively defined by his long-standing professional relationship with the protagonist, Golgo 13. He is the go-to specialist that Golgo contacts when a mission requires a custom weapon, specialized bullet, or a modification that defies conventional engineering. Over the years, their relationship has developed into a mutual, if begrudging, respect and a "long-running, inextricable" bond. McCartney is one of the very few characters who can speak informally to Golgo, using a familiar tone and even refusing to do things he considers an impediment to his work. In turn, Golgo recognizes McCartney's skill, expressing gratitude for a job well done, a gesture he rarely offers anyone else. The nature of their partnership is such that McCartney has even been forcibly taken, or effectively kidnapped, by Golgo to work on urgent, on-location projects when there was no time for delivery.

While his primary motivation is the high payment he receives for his dangerous work, McCartney is also driven by his professional pride. The technical challenges presented by Golgo's requests appeal to his ego, and his complaints often mask a willingness to push the boundaries of his craft. His development as a character is most notably marked by becoming the protagonist of his own spin-off manga series titled Gunsmith Dave, which began serialization in 2021, highlighting his significance within the fictional universe. Among his many notable abilities are producing a rifle capable of a one-kilometer precision shot in just three hours, creating a recoilless M16 for use in the vacuum of space, and designing bullets that can liquefy to destroy evidence or penetrate tank armor. While there has been one instance of an incomplete job, it was due to client demands, and he has never otherwise broken a promise or failed to meet an expectation.