This post was originally published on Audible.com.

The Sandman is a comic book series filled with fascinating characters and mythology, which recently became a full-cast audio experience adapted and directed by Dirk Maggs, a renowned pioneer in the medium. It's easy for the world of the Sandman series to stretch far beyond the original comics and its many spin-offs. The Sandman is popular fodder for crossovers, and the comic’s cast has found their way into all sorts of stories, interacting with characters ranging from Batman to Thanos—yes, Marvel's Thanos! No worries: If you want to keep track of it all, we've got you covered. 

The Sandman is a comic series written by Neil Gaiman and published by DC Comics. The story follows Dream, also known as Morpheus, who, along with his siblings Destiny, Death, Desire, Despair, Delirium, and Destruction, is one of the Endless, anthropomorphic embodiments of powerful natural forces. At the start of the series, Morpheus has been captured by an occult ritual and held prisoner for 70 years. When he escapes, he finds himself in the modern world and sets out to rebuild his kingdom. 

The original Sandman series is 75 issues long and ran from January 1989 to March 1996. But just because the main Sandman comics officially ended in 1996 doesn't mean its characters haven't lived on in other ways. Along with spin-offs and adaptations, The Sandman has been a part of several crossovers.

But what are crossovers, you ask? Crossovers have been used throughout different types of media to connect characters and storylines across different properties. We see crossovers a lot in comic books because they allow characters to interact within a shared universe and create a through line of a consistent reality across various comic book series. 

The Sandman crossovers are challenging endeavors because the Sandman comic series takes place in an alternate universe and not the main DC Comics universe. But that doesn't mean Sandman crossovers are impossible; in fact, there have been plenty of them. Here's a rundown of all existing Sandman crossovers, the characters involved, and where they appear. 

Green Arrow (Volume 3)

The Green Arrow comics may not bring back any Sandman characters but they do feature a significant Sandman prop: the Magdalene Grimoire. The Grimoire is a book full of occult ceremonies, incantations, mystic rites, and summoning spells. And you guessed it—this very book was used to capture Morpheus way back at the beginning of the Sandman comic series. The Grimoire shows up again in #9 and #10 of the Green Arrow comics (Volume 3) and is used to try to bring Oliver Queen (the Green Arrow) back from the dead.

Swamp Thing (Volumes 1 & 2)

Matthew Cable is a character that has appeared in many issues of The Sandman, but he's also in multiple issues of DC's Swamp Thing series. Although Matthew Cable died in Swamp Thing, he appears in The Sandman, resurrected by Morpheus as a raven. In raven form, Matthew becomes a loyal servant to Morpheus, often offering him advice and going on missions for him. 

The Incredible Hulk #418

One of the most beloved Sandman characters is Death. In fact, she's such a fan favorite that she couldn't just stay on the pages of DC comics alone. So, Death also found her way into the Marvel universe. Although she is never directly identified, Death is unmistakably at the wedding of Rick and Marlo who have been resurrected from the dead in The Incredible Hulk #418. Marlo sees a pale-skinned woman with dark hair wearing all black. When Marlo asks the woman if they've met before, she simply says, "Briefly." It's also heavily suggested here that Death is the same Lady Death that Thanos fell in love with. 

Action Comics #894

Guess who's back? It's Death, of course, this time making an appearance in Lex Luthor's Action Comics #894. This issue starts with Lex Luthor's spectral self looking over his lifeless body. With him is Death, who tells him that he's actually not dead yet—she just wanted to check in on him. And with that, he is returned to his body. Reflecting on what has just happened to him, Lex Luthor realizes Death appeared to teach him an important lesson. 

The Brave and the Bold: The Lords of Luck

Destiny is the only Sandman character who wasn't originally created by Neil Gaiman, and he appears in many other comics outside of the Sandman comic series. Most notably, Destiny shows up in The Brave and the Bold: The Lords of Luck. In chapter four, Supergirl and Lobo cross paths with Destiny as they're searching for the Book of Souls. Destiny explains he's been the guardian of the book since the Dawn of Time. In recent years, however, the Book of Souls has been rewritten and destiny has been corrupted. Destiny admits: he's unsure of how to fix it. 

JLA (Volume 1)

Daniel Hall, the successor to Morpheus as Sandman, appears in Volume 1 of the Justice League of America. He shows up to help with an invasion of Starro. "I have a million faces," he explains. "Once my name was Daniel. I am the King of Dreams. Call me Sandman if that fits more comfortably into your frame of reference." It does. 

Dark Nights: Metal

Big spoiler warning for those who haven't read Dark Nights: Metal, because this appearance was a big twist for fans of the comics. Okay, are you ready? Daniel Hall returns to talk to Batman at the end of Dark Nights: Metal (Vol 1) and warn the superhero about future dangers. This appearance from Morpheus's successor was surprising and felt ominous for comic book fans. 

Locke & Key/The Sandman Universe: Hell & Gone

Fans of dark fantasy comics could hardly wait for the Sandman crossover with Joe Hill's Locke & Key. Locke & Key follows the story of the Locke family. Keyhouse, the Lockes's ancestral home in Lovecraft, Massachusetts, is filled with an array of magical keys. There's one key that can open people's minds, another that can turn you into a ghost, and others that open fantastic doors into worlds impossible to fathom. Siblings Tyler, Kinsey, and Bode Locke explore the house and discover its secrets—including some pretty terrifying ones.

So, how does The Sandman fit into the world of Locke & Key? Locke & Key/The Sandman Universe: Hell & Gone will connect the Locke family to the realm of The Dreaming through Lucifer's Key to Hell. The story follows Mary Locke as she descends to Hell in an effort to save her brother John's soul. The highly anticipated crossover is written by Hill and, like every issue of Locke & Key, illustrated by Gabriel Rodríguez.

And speaking of highly anticipated... Sandman fans can look forward to entering the Dreaming again this fall with the release of The Sandman: Act II, the sequel to the best-selling audio adaption of Neil Gaiman's sensational graphic novel.

Emily Martin is a Contributing Editor at Book Riot and podcasts/blogs with Book Squad Goals. She has an MFA in Creative Writing, a PhD in English, three cats, and way too many books.