Diamond Comic Distributors, Inc. (often called Diamond Comics, DCD, or casually Diamond) is an American comic book distributor serving retailers in North America and worldwide. It transports comic books and graphic novels, as well as other popular culture products such as toys, games, and apparel, from comic book publishers or suppliers to retailers.

It is owned by Geppi Family Enterprises, which is also the parent company of Alliance Game Distributors, Diamond Book Distributors, Diamond UK, Diamond Select Toys, Gemstone Publishing, E. Gerber Products, Diamond International Galleries, Hake's Americana & Collectibles, Morphy's Auctions, the Geppi's Entertainment Museum, and Baltimore magazine. On May 16th 2025 the company was sold to Sparkle Pop, a subsidiary of Ad Populum. The acquisition included several companies under the Geppi Family Ent umbrella.

Diamond is the publisher of Previews, a monthly catalog/magazine showcasing upcoming comic books, graphic novels, toys, and other pop-culture merchandise.

In 1982, Baltimore-based comics retailer Steve Geppi founded Diamond Comic Distributors. Diamond became the successor to direct-sales pioneer Phil Seuling's distribution dream when it took over New Media/Irjax's warehouses in 1982. Diamond further bought out early distributor Bud Plant Inc. in 1988, and main rival Capital City Distribution in 1996, to assume a near-monopoly on comics distribution, including exclusivity deals with the major comic book publishers.

By 1981/1982 Geppi had four comics retail locations and was already "doing a little informal distributing... for smaller retailers." Geppi found himself "one of the biggest accounts" for New Media/Irjax, and when the distributor "relocated to Florida, he asked Geppi to service more accounts for a bigger discount." One of the "last loyal customers" when New Media began having fiscal difficulties, Geppi made a deal: "[t]he owner was going into retail," so Geppi agreed to provide New Media/Irjax with "free books for a period of time in return for his account list," buying parts of the company, and founding Diamond Comic Distribution.

Geppi had been a sub-distributor for Hal Shuster's Irjax in the late 1970s. In what Mile High Comics' Chuck Rozanski describes as an "incredibly risky and gutsy move," Geppi took over New Media/Irjax's "office and warehouse space" and, recalled Rozanski, had to "sort out the good customers from the bad overnight" negotiating with creditors to continue Shuster's distribution business as Diamond Comic Distribution. Almost overnight, noted Rozanski, "[h]e went from being a retailer in Baltimore to having warehouses all over the place."

Geppi named his new company 'Diamond' "after the imprint Marvel Comics used on non-returnable comics," and although the "publisher discontinued the symbol" months later, the name remained. "Diamond grew an average of 40 percent a year," as comics retail took off.

In 1983, Diamond hired an accounting firm. In 1985, Diamond hired "no-nonsense CPA" Chuck Parker "as Diamond's first controller". In 1994, Diamond employee Mark Herr noted that this move was Geppi's "best decision", as Parker "cares nothing about the comics. To him, it's dollars and cents." Parker describes his role as "smooth[ing] the emotion out of some decisions. Steve [Geppi] is a visionary and a risk-taker... and I tend to be more conservative."