WARNING: The following contains spoilers for Ruins of Ravencroft: Sabretooth #1 by Frank Tieri, Angel Unzueta, Guillermo Sanna, Rachelle Rosenberg and Travis Lanham, on sale now.

In the Ruins of Ravencroft series, we've already learned a lot about the secret history of the Marvel Universe. As it turns out, the formation of the asylum that usually holds some of Spider-Man's most dangerous villains is connected to some of Marvel's most notable superheroes, monsters and aliens.

Long before Ravencroft was really established,  Cletus Kasady's ancestor, Cortland Kasady, first learned of Knull, before turning into the New World's first serial killer. The site of the institute was also where Wolverine and Sabretooth had their first fight and where the Colonial Captain America, Steve Rogers' ancestor Steven Rogers, fell in the closing moments of the Revolutionary War.

These secrets have all been unearthed thanks to Jonas Ravencroft's recently discovered journal. As Ruins of Ravencroft: Sabretooth #1 continues to unravel the institution's secrets, we learn that the legendary Headless Horseman was a figure within the Marvel Universe, and he was also one of Marvel's Spirits of Vengeance, a Ghost Rider.

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The Headless Horseman is a legendary figure who was reconceptualized for America by Washington Irving in The Legend of Sleepy Hollow. As the character's name suggests, he was a horseman without a head who terrorized the little American town during colonial times. He is often portrayed with a flaming pumpkin, and he's become one of the most enduring figures in American folklore. , Ruins of Ravencroft: Sabretooth #1 confirms the character existed in the Marvel Universe and reveals that he was one of Marvel's Spirits of Vengeance in 1820.

As the character's one-panel appearance shows, the Headless Horseman of the Marvel Universe holds not a flaming pumpkin but his own flaming skull, and he rides a steed powered by his hellfire. While this revelation is surprising, it still makes a degree of sense. All the elements of the Headless Horseman legend, from his horse to the flames and his head, lend themselves perfectly to the Ghost Rider mythos.

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During a recent trip to Hell in Avengers. Marvel's current Ghost Rider, Robbie Reyes, encountered all of the characters who preceded him as the Spirit of Vengeance, even dating back to the Earth's first mammoth-riding Ghost Rider. While the Headless Horseman did not appear there, he could've simply been off-panel.

Even though Ruins of Ravencroft is ostensibly more about unearthing the past than setting up the future, the introduction of the Headless Horseman Ghost Rider is just one of the many tantalizing secrets that the series has revealed that hint at ideas that beg to be followed upon. Hopefully, it won't be long before Marvel reveals some more details about Sleepy Hollow's most famous legend.

KEEP READING: The Ravencroft Institute, Marvel's 'Arkham Asylum,' Explained