These days, many devotees of contemporary science fiction and horror pay scant attention to the rich past of their genres, and yet such neglect makes little sense: When you love a subject, don’t you want to know everything you can about that subject, including its history?

In “The Visual History of Science Fiction Fandom — Volume One: The 1930s,” David and Daniel Ritter — a ­father-and-son team — show us, through words and pictures, how a passion for science fiction evolved into a way of life for young people who couldn’t get enough of that crazy Buck Rogers stuff. The result is a sumptuous scrapbook of photographs, magazine covers, artwork and hundreds of articles, letters and typescripts, everything beautifully held together by the Ritters’ concise but enthralling text. The physical book is expensive but, given the amount of material in it and the high quality of the printing, one doubts that First Fandom Experience is doing more than breaking even. Happily, there is a less costly digital version available for e-readers.

Whatever the format, this labor of love demonstrates how much today’s science fiction fandom owes to its past. For instance, did you know that cosplay — dressing up like fictional characters — existed long before San Diego ­Comic-Con? The Ritters print a 1939 photograph of young Forrest J. Ackerman — in later life, editor of the magazine Famous Monsters of Filmland — and Myrtle R. Douglas (sometimes known as Morojo) appareled in superhero get-ups at the very first World Science Fiction Convention.

Most of us think of blogs and home pages as strictly 21st century, but think again. At heart, they are superpowered versions of 1930s fanzines, those mimeographed, self-published journals in which amateurs wrote stories and criticism, often with the hope of becoming, in an affectionate phrase, “a dirty pro.” Similarly, while the internecine flame wars of contemporary sci-fi burn through our social media, they are nothing new: From the beginning, fandom has been alternating between intense collegiality and five-alarm factionalism.

As this documentary cornucopia reminds us, modern American science fiction dates from the launch of Amazing Stories in 1926. In the August 1927 issue — beloved for its “War of the Worlds” cover by Frank R. Paul — there appeared a letter from a reader about setting up a science fiction club. The Ritters reproduce that letter. A few pages later you can read Hugo Gernsback’s actual article announcing the formation of the Science Fiction League. There follow pages from the Time Traveller, the Fantasy Fan and other early fanzines.

In 1933 two Cleveland teenagers — Jerry Siegel and Joe Shuster — used their zine to publish “The Reign of the Super-Man.” Five years later, Superman, now without the hyphen, was lifting up a car on the cover of Action Comics No. 1 (currently selling for a million dollars in decent condition). A long section describes the origin of Conan of Cimmeria, highlighting Robert E. Howard’s background essay “The Hyborian Age” as it appeared in the Phantagraph. Other chapters look at the first regional sci-fi conventions, the cultural impact of “King Kong,” fannish artwork, the creation of the spoof god Ghu and his rival Foo, the British science fiction scene and the early careers of the editors Donald A. Wollheim, Raymond Palmer and John W. Campbell Jr.

Many professional writers first entered the field as fans, including Isaac Asimov, Frederik Pohl and Ray Bradbury. So vast is the Ritters’ reach that some of Pohl’s youthful poetry is reprinted here, along with letters from the blistering satirist Cyril Kornbluth. In 1953, Pohl and Kornbluth would collaborate on their classic dystopian novel, “The Space Merchants,” about a future governed by transnational corporations who use Madison Avenue hype to manipulate the population of an environmentally devastated world. Sounds pretty far-fetched, right?

While I’ve barely done more than ooh and aah over “The Visual History of Science Fiction Fandom,” I want to add that some of its scarcest material was acquired from Robert A. Madle, a Rockville, Md., book and magazine dealer who will be 100 this June. Madle is one of our last living connection to the 1939 Worldcon and fandom’s first tumultuous ­decade.

Jess Nevins, author of “Horror Fiction in the 20th Century,” is not only widely read but also seemingly tireless. He has annotated Alan Moore’s graphic novels about the League of Extraordinary Gentlemen, written “The Evolution of the Costumed Avenger: The 4,000 Year History of the Superhero,” and just this month brought out, as an e-text only, a second, much expanded edition of his Encyclopedia of Fantastic Victoriana, a survey of what one might call 19th-century pulp fiction.

In the first third of “Horror Fiction in the 20th Century,” Nevins focuses on the old masters: Arthur Machen, Algernon Blackwood, Oliver Onions, H.P. Lovecraft and many others. Unfathomably, however, he summarizes their work without mentioning any specific titles. One may also question some judgments: M.R. James’s ghost stories aren’t really cozy or humorless; they can be quite grisly — a necromancer tears out the hearts of small children — and many of the characters are comically Dickensian. Nevins also seems overly fixated on whether a writer originated or merely popularized a particular literary trope.

Still, in the latter two-thirds of his book, Nevins casts an extremely wide net, providing brief critical introductions to modern authors as various as Thomas M. Disch, Jonathan Carroll, Robert Westall, Fred Chappell, Ben Okri, Joyce Carol Oates and John Bellairs. Even more groundbreaking chapters point us to important horror writers outside the Anglo-American tradition. Not least, Nevins champions inclusivity. He discusses Vincent Virga’s “Gaywyck” (1980), the first openly gay modern Gothic, and catalogues the Afro-Gothic elements in Ann Petry’s classic “The Street” (1946). Still, in too many cases, readers wanting to know the titles of an author’s key works will be left frustratingly in the dark.

Michael Dirda reviews books each Thursday in Style.

THE VISUAL HISTORY OF SCIENCE FICTION FANDOM

Volume One: The 1930s

By David Ritter and Daniel Ritter,

With Jeff Diperna and Wendy Gonick

First Fandom Experience. 515 pp. Hardcover, $150; E-Book, $39

HORROR FICTION IN THE 20TH CENTURY

Exploring Literature's Most Chilling Genre

By Jess Nevins

Praeger. 277 pp. $49.95; ebook, $40

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