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 (or lettercols), 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. Letter columns remained a regular feature of most comic books until the early years of the 21st century, when they were gradually phased out in favor of the growing prevalence of email and Internet fora.
Although they were already standard in the science fiction magazines of the time, the first recorded comic book letter column appeared in Target Comics #6, published by Novelty Press in 1940. (The page in question also has an early mention of comic book collecting.) The first DC Comics comic to include a letters column was Real Fact Comics #3 (Jul-Aug 1946). The first DC title with a letters column as a regular feature was Superman beginning with issue #124 (September 1958).
Early versions of the lettercol tended to be simple fan letters, often from young readers. These letters tended to be praise for the previous issue's story and artwork; or simplistic questions about the correct pronunciation of "Mxyzptlk" or where Superman put his Clark Kent clothes when he was in costume; or alternately, obsessive dissections of perceived continuity errors or art mistakes.
Letter columns came into their prime in the 1960s, when readers' letters became longer and the discussions more sophisticated. For example, in the mid-1960s longtime letter writer (and future comics historian) Peter Sanderson's lengthy, well-reasoned, and impressively erudite missives forced DC editor Julie Schwartz to expand the lettercols in his books to a second, separate page (such as "Flash-Grams — Extra", "Letters To the Batcave — Extra", and "JLA Mailroom — Special Peter Sanderson Edition") to facilitate Sanderson's sharp analysis.