Horror comics are comic books, graphic novels, black-and-white comics magazines, and manga focusing on horror fiction. In the US market, horror comic books reached a peak in the late 1940s through the mid-1950s, when concern over content and the imposition of the self-censorship Comics Code Authority contributed to the demise of many titles and the toning down of others. Black-and-white horror-comics magazines, which did not fall under the Code, flourished from the mid-1960s through the early 1980s from a variety of publishers. Mainstream American color comic books experienced a horror resurgence in the 1970s, following a loosening of the Code. While the genre has had greater and lesser periods of popularity, it occupies a firm niche in comics as of the 2010s.

Precursors to horror comics include detective and crime comics that incorporated horror motifs into their graphics, and early superhero stories that sometimes included the likes of ghouls and vampires. Individual horror stories appeared as early as 1940. The first dedicated horror comic books appear to be Gilberton Publications' Classic Comics #13 (August 1943), with its full-length adaptation of Robert Louis Stevenson's Strange Case of Dr Jekyll and Mr Hyde, and Avon Publications' anthology Eerie #1 (January 1947), the first horror comic with original content. The first horror-comics series is the anthology Adventures into the Unknown, premiering in 1948 from American Comics Group, initially under the imprint B&I Publishing.

The horror tradition in sequential-art narrative traces back to at least the 12th-century Heian period Japanese scroll "Gaki Zoshi", or the scroll of hungry ghosts (紙本著色餓鬼草紙) and the 16th-century Mixtec codices.

In the early 20th-century, pulp magazines developed the horror subgenre "weird menace", which featured sadistic villains and graphic scenes of torture and brutality. The first such title, Popular Publications' Dime Mystery, began as a straight crime fiction magazine but evolved by 1933 under the influence of Grand Guignol theater. Other publishers eventually joined in, though Popular dominated the field with Dime Mystery, Horror Stories, and Terror Tales. While most weird-menace stories were resolved with rational explanations, some involved the supernatural.

After the fledgling medium of comic books became established by the late 1930s, horror-fiction elements began appearing in superhero stories, with vampires, misshapen creatures, mad scientists and other tropes that bore the influence of the Universal horror films of the 1930s and other sources.

In 1935, National Periodicals published the first story of Doctor Occult by Jerry Siegel (script) and Joe Shuster (Art) in New Fun Comics # 6, where he confronts Vampire Master. In Detective Comics # 31–32, Batman fights a vampire.

By the mid-1940s, some detective and crime comics had incorporated horror motifs such as spiders and eyeballs into their graphics, and occasionally featured stories adapted from the literary horror tales of Edgar Allan Poe or other writers, or stories from the pulps and radio programs. The single-issue Harvey Comics anthologies Front Page Comic Book (1945), bearing a cover with a knife-wielding, skeletal ghoul, and Strange Story (July 1946), introduced writer-artist Bob Powell's character the Man in Black, an early comic-book example of the type of omniscient-observer host used in such contemporary supernatural and suspense radio dramas as Inner Sanctum, Suspense, and The Whistler.

As cultural historian David Hajdu notes, comic-book horror: