The 13th Warrior, aka Eaters of the Dead is an adventure story that inserts the Real Life Arabic traveler Ahmad ibn Fadlan into Beowulf. Ahmad ibn Fadlan is an educated Arab courtier who is sent to foreign lands as punishment for a courtly indiscretion. He is recruited to serve as the thirteenth member of a group of Norse warriors who answer a call for help from a far-away Nordic king. The kingdom is under attack from inhuman mist-dwellers known as the Wendol. The bookish Ahmad ibn Fadlan narrates his adventure and his growing respect for the barbarians around him.
The story is a reworking of the classical tale of Beowulf. Buliwyf is an Expy for the hero Beowulf and the remaining warriors form his band. The Grendel and his mother are replaced with the cannibalistic Wendol, who appear to be neanderthals who worship a cannabalistic fertility goddess called the mother of the Wendol. Rather than Grendel bursting into a mead hall, a group of cannibals attack. Rather than attacking Grendel's aquatic mother, the band sneaks into the Wendol's temple to the Mother through water. Rather than a dragon, the mounted Wendol attack force looks like a "glow wyrm" when holding torches aloft.
Michael Crichton wrote the novel, and it was something of a departure from his usual science-fiction fare. He supposedly wrote it on a dare from a friend who demanded he "find a way to make Beowulf interesting". As Crichton was aware of the notoriously dry, bland Ahmad ibn Fadlan and his ability to make any miraculous new wonder sound prosaic and dull, he put the two together as if it were Ahmad giving an actual historical account. The Neanderthals serving as the villains are an expected flourish of science fiction.
The novel was later adapted into a feature film starring Antonio Banderas and directed by John McTiernan. Crichton himself performed some reshoots after test screenings. For the release of the film, some printings renamed the book after the film, with the note "Originally Published As 'Eaters of the Dead'".
The novel provides examples of:
- Adaptational Villainy: Wigliff is a Composite Character of Hrothgar's two sons (Hrethdric and Hrothmund), Unferth and Wiglaf from the original epic, with every positive trait removed and a lot of negative ones (cowardice, jealousy, physical weakness) added. Like Unferth, he taunts Buliwyf when he arrives in Hurot and is silenced by being exposed as a fratricidal killer, but he doesn't reconcile with him and doesn't give him a weapon to kill Grendel's mother. He later insults Buliwyf after he dies from the mother's poison and is killed in a duel by Herger, while in the poem Wiglaf killed the dragon after Beowulf was mortally wounded, and Beowulf willed his kingdom to him.
- Adaptation Distillation: Of Beowulf, interwoven with the real-life writings of Ahmad ibn Fadlan. Besides heavy doses of Demythification, the story never leaves Hurot (Heorot) after the main characters get there, while the original Beowulf moves on to Buliwyf/Beowulf's homeland and describes his last battle as happening in his old age.
- All Cavemen Were Neanderthals: And cannibals to boot. They seem to especially prize collecting heads in order to eat the brains.
- Anachronism Stew:
- While Beowulf may have been written at any point between the 8th and 10th century, the earlier date is more generally agreed, and the story's Hrothgar is believed to have been a historical king in 6th century Denmark, much earlier than Ibn Fadlan.
- The Wendol are Neanderthals who live in Viking Age Scandinavia, worship Venus figurines (a Homo sapiens artifact) and ride horses.
- Barbarian Tribe: The Northmen (from Ahmad's perspective, along with the many non-Muslim peoples he meets as an ambassador before them), and of course the Wendol, who are said to be Neanderthals.
- Bears Are Bad News: The Wendol intentionally invoke this as part of their disguise, weapons and style of fighting.
- Black Is Bigger in Bed: Deconstructed. Every culture apparently has this myth about one ethnic group or another. The Nordic women encountered by the Arabic narrator assume he'll be massively endowed; being well-traveled, he remarks that he's heard identical rumors in most countries, usually about a population that lives far away from whoever is spreading the rumor.
- City Mouse: Ahmad, who is, after all, a travelling writer in the book and banished court poet in the movie. It's addressed numerous times by different characters how unmanly and whiny he is.
- Composite Character: A bizarre case is Wigliff, Hrothgar's son. In Norse mythology, Hrothgar has two sons who are too young to fight when Grendel attacks, hence why they can't be relied on to fight him. The character who taunts Beowulf and is silenced by being reminded about being a fratricidal killer is a courtier named Unferth. Unlike Wigliff, Unferth reconciles with Beowulf and gives him his family's sword to kill Grendel's mother. For added confusion, he is obviously named after Wiglaf, who in the poem joins Beowulf's retinue years later and succeeds him as king after killing the dragon that kills Beowulf.
- Deliberate Values Dissonance: Ahmad's worldview clashes with the Norse just as much as the reader's. For instance, the Norse consider 13 a lucky number.
- Demythification: One of the more obvious examples of the trope, since Crichton wrote the book exactly as such.
- Grendel, a beast-like man with the strength of several men, who cannot be hurt by bladed weapons and is capable of ravaging a community for twelve years, is substitued by the Wendol, a tribe of relict neanderthals in bear skins with No One Gets Left Behind (even the dead) as a creed. Grendel's severed arm (his first, and eventually fatal injury) is changed to a Wendol's severed arm being the first evidence that they are corporeal beings that can be wounded and killed.
- The Wendol's "mother" is their leader, an elderly matriarch. She shrieks and is hideously old, but she doesn't really put up a fight. However, she keeps living snakes over her body and uses their venom as a weapon. This is why Buliwyf kills her alone: he is still the only one that dares to get closer to the snakes.
- Before fighting the mother, the Northmen visit a "tribe" of dwarves. Norse dwarves kept in an isolated community by the others, who believe them to have magical powers. They give the Norse "magical" daggers to kill the mother and Buliwyf uses one to do it. Ahmad is skeptical whether the dwarves really have magical powers, but his companions certainly believe they do.
- The dragon is an optical effect, the sight of torches carried by Wendol raiders mounted on horses. The effect is amplified because they only attack at night and under the cover of the mist.
- Doing In the Wizard: Most mystical elements from Beowulf are taken out, but the dwarf seers are pretty accurate.
- The Drag-Along: Ahmad is a lot slower in becoming a badass than his movie counterpart.
- The Dreaded: At the beginning, the Vikings have real terror for the Wendol, and the legends that surround them. When Rothgar/Hrothgar asks them for help in fighting "an ancient evil — a terror that must not be named", the Vikings are so subdued that Ahmad ponders "What thing could affect them so?" As the warriors approach Rothgar's kingdom, Ahmad writes, "I looked at Ecthgow, the lieutenant of Buliwyf, and saw that he stood in the boat and made a brave face, and yet his knees trembled, and it was not the stiffness of the wind that made them tremble so. He was afraid; they were all afraid; and I did not know why."
- Fan Disservice: The Wendol are naked under their bear skins, though they are more hairy than humans. The Wendol mother wears living snakes instead of bear skins and is "so old she had lost all the characters of her sex."
- Foreign Correspondent: Ahmad, being an Arab, is puzzled by many things common in Norse culture. However, being a 10th century Arab, he himself has beliefs in dissonance with modern readers. Notably he perceives the Northmen as being too soft on their slaves.
- Going Native: Ahmad begins to adopt Viking culture more and more, culminating with his sleeping with and helping strangle the girl chosen for a Viking Funeral. In the film version it's almost entirely omitted.
- Hidden Elf Village: The Wendol caves. Subverted with the dwarf community, which only exists because the Norse leave their dwarf children there.
- I'm a Humanitarian: The Wendol ritualistically collect their victim's heads and eat the brains, hence the book's name.
- Lost World: The refuge of the Wendol. Like in the movie, the limits of their territory are marked by posts with bear skulls, but the book says that they are much larger than common bear skulls, implying that they are cave bears. It is not established if cave bears are also still alive in the mountains around Hurot, however.
- The Low Middle Ages: The action takes places during The Viking Age.
- No Ending: The manuscript, and thus the book, ends just before Ahmad ibn Fadlan is about to embark on a new adventure, practically in the middle of-
- Which is part of Crichton showing his work, as historians often have to deal with sources that have been partially lo-
- Off with His Head!: The Wendol steal the heads of those they kill, including some of Buliwyf's men.
- The Reveal: Ahmad gets a clear view of a Wendol without his bear skin and describes his features in detail. It's indisputably a Neanderthal. The book's epilogue includes various academic authorities arguing over whether Ahmad's description of the Wendol can be trusted.
- Sea Monster: When Ahmad sees whales in the Baltic for the first time in his life, the Norse tell him that they are sea monsters and that they destroy ships because they mistake them for potential mates. It is as unclear to Ahmad, the reader and the in-universe translators if the Norse really believe this or they are just pranking Ahmad.
- Setting Update: The immediately post-Roman story of Beowulf is moved forward to the Viking Age.
- Shown Their Work: As is typical of him, Crichton displays his erudition. His worldbuilding was and is so convincing that years later, not even he sometimes couldn't tell which parts he made up and which were from Ahmad ibn Fadlan's real writings. He said one of the annoying parts was that he'd fabricated his references so well that he'd spend hours trying to look up a book, and sometimes still wasn't sure whether he just couldn't find it or if he'd made it up himself.
- 13 Is Unlucky: Well, it was certainly unlucky for Ahmad to be picked as the 13th warrior of the party. But the Norse consider 13 a lucky number, and Ahmad is one of the few that survives to tell the tale.
- Twice-Told Tale: Beowulf.
- You Can't Fight Fate: Ahmad is forced to go with the Vikings because their oracle said so ("the party... must be thirteen, and of these one must be no Northman"), and they won't discuss it further.