National Comic Book Day is here: 18 essential graphic novels to add to your bookshelf

(Image credit: DC, Marvel, Dark Horse) It's National Comic Book Day, one of the two big days on the calendar where fans celebrate this amazing medium. (The other is Free Comic Book Day, which usually takes place in May.)For this article, I've pulled together a list of 18 essential graphic novels, divided into three subsets: DC, Marvel, and a special section for those of you who want to read something other than superhero comics.It's a list that's packed full of all-time classics, from the amazing All Star Superman (which heavily inspired the recent film), to Secret Wars (so you can get ahead of next year's Avengers movie) and my two personal favorite comics of all time: The Invisibles and From Hell. Really, though, this list could easily have been three times as long and still not scratched the surface of what comics have to offer.DC superheroesMarvel superheroesIf you don't like superheroes...Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. Get instant access to breaking news, the hottest reviews, great deals and helpful tips. Will Salmon is Tom's Guide's Collections Editor, curating advice on the best products to spend your money on. Will has been writing about tech and entertainment for almost 20 years, including stints as GamesRadar+'s Streaming Editor, editing comics website Newsarama, and writing for lots and lots of magazines. You can read his work in SFX magazine, GamesRadar+, and right here on Tom's Guide.