A comic book letter column is a section of an American comic book where readers' letters to the publisher appear. Comic book letter columns are also commonly referred to as letter columns, letter pages, letters of comment (LOCs), or simply letters to the editor. Letter columns appeared early on in the history of comic books themselves, and their growing prevalence — particularly beginning in the 1960s — helped create and legitimatize comics fandom. As the forum developed, the volume and tenor of letters became a reliable gauge of overall reader response to developments in the comics themselves. Letter columns remained a regular feature of most comic books until the early years of the 21st century, when they began being phased out in favor of the growing prevalence of email and Internet forums. Despite this, the 2010s saw a renaissance of comic book letter columns, and many comics titles still print them.

An American comic book is a thin periodical originating in the United States, on average 32 pages, containing comics. While the form originated in 1933, American comic books first gained popularity after the 1938 publication of Action Comics, which included the debut of the superhero Superman. This was followed by a superhero boom that lasted until the end of World War II. After the war, while superheroes were marginalized, the comic book industry rapidly expanded and genres such as horror, crime, science fiction and romance became popular. The 1950s saw a gradual decline, due to a shift away from print media in the wake of television and the impact of the Comics Code Authority. The late 1950s and the 1960s saw a superhero revival and superheroes remained the dominant character archetype throughout the late 20th century into the 21st century.