The differences between J.R.R. Tolkien's book The Fellowship of the Ring and the Peter Jackson film screenplay of the same name are fairly easy to document because, in both the book and film, the story maintains a single thread from beginning to end. While there are some changes in sequence, the storyline is well aligned between the two sources. The differences between them are described here in considerable detail. The order is intended to be that of the film, and it is also the intent that this article should eventually include all significant differences between the book and film.
- In the prologue, Isildur grabs for his father's (unbroken) sword, Sauron steps on it, breaking it, and then Isildur uses the broken sword to kill Sauron by cutting off his fingers (including the finger with the One Ring). In the book, Sauron is already defeated (and his body lifeless), and the sword is already broken when Isildur takes it from under his father Elendil's dead body and uses it to cut the ring from Sauron's hand.
Additionally, the screenplay shows clearly that most if not all of the fingers on one of Sauron's (possibly left) hand are severed. But Gollum says in the book that he has nine fingers "but they are enough, precious, they are enough!". Here Gollum perhaps refers to Sauron torturing him, perhaps by touching Gollum's fingers with his own, which were "black and burning hot;" in the film, Gollum is tortured only by orcs using a rack.
- While Gandalf is talking to Elrond in Rivendell in the movie, a flashback shows Elrond leading Isildur into the fiery mountain, Orodruin, and bidding him throw the Ring into the Cracks of Doom. In the book, Elrond and the Elf-lord Círdan, standing with Isildur beside their dead, counseled Isildur to take the Ring into the mountain and throw it into the Cracks of Doom near at hand, but Isildur refused and took the Ring instead as weregild for the death of his father.
- In the movie, the mischief of Merry and Pippin in launching Gandalf's best rocket was a fabrication of the screenplay. This did not occur in the book; rather, the dragon-firework was Gandalf's tribute to Bilbo, for his helping to defeat the dragon Smaug... as well as to signal supper-time.
- In the movie, when Bilbo put on the Ring, he just vanished, much to the shock and dismay of the onlookers. In the book, this was to be a little joke of his, of which Gandalf and Frodo were in the know. Gandalf did not much approve of this because, "magic rings were not to be trifled with." Without Bilbo's knowledge, Gandalf had prepared a trick of his own to provide an explanation for his disappearance. At the moment he vanished, Gandalf threw a blinding flash. In addition to scaring the wits out of Bilbo, who had not expected it, this gave the partygoers a "culprit", and Gandalf was blamed by many for spiriting Bilbo away.
- In the movie, the time between Bilbo's departure from the Shire and Frodo's does not seem to have been much more than a year. The only clue that it might have been longer was the amount Bilbo seemed to have aged when Frodo next sees him in Rivendell, but that aging could have been attributable to his no longer possessing the Ring. Many people assume that it was only a few months in the movie, but that wouldn't explain why Frodo arrives in Rivendell in October (like in the book) after Bilbo's birthday in September. It had to have been at least a year; Gandalf probably returned around Bilbo's 112th birthday in the movie. In the book, their respective departures were separated by a period of exactly seventeen years, and Bilbo did age much more in that time than he would have normally as a result of the loss of the Ring. The Hobbit: The Battle of the Five Armies confirms that the time gap was much smaller, when stating that Aragorn is already a Ranger and known among his people. According to Tolkien's timeline, he would only have been ten at the time, and his age during the events of the Lord of the Rings was confirmed by the Two Towers' Extended Cut to match the books.
- In the movie, Gandalf's journey included only the trip to Minas Tirith. In the book, that journey was taken for the purpose of finding and capturing Gollum—a quest in which Aragorn aided him. It was only when he despaired of doing so that Gandalf remembered the words of Saruman about the writing on the Ring, prompting him to search for the scroll of Isildur, which might make the finding of Gollum unnecessary. After Gandalf forsook the quest and turned toward the White City, Aragorn found Gollum and bestowed him into the keeping of the Wood-elves as had been agreed between him and Gandalf. (Note: Legolas was a Wood-elf.) On his return from Minas Tirith, Gandalf came to the Woodland Realm and interrogated Gollum. It was from this that Gandalf learned how the Ring had been found by Deagol, of the murder of Deagol by Sméagol (who is Gollum), of the turning out of Gollum by his kin, of Gollum's flight into the subterranean caves below the Misty Mountains, and of his account of his loss of the Ring. From the many things that were said and known, Gandalf also inferred the distant relationship between Gollum's people and the hobbits(a fan movie was created based on these events, with the main protagonist Aragorn capturing Gollum). This journey by Gandalf took a period of about nine years after which time he returned unexpectedly to Hobbiton to make that final "test" to prove what he already knew—that the hobbit's ring was the Ruling Ring.
- In the film, Gandalf openly tells Saruman that the Ruling Ring has been found in possession of the hobbits in the Shire. In the book, Gandalf never reveals this information to him. Saruman must deduce it based on information that he obtains from various sources, and he is never able to find out anything in detail about where, exactly, the Ring might be or in whose possession.
- A total of four chapters and parts of a fifth are completely missing from the screenplay. The chapters are, 'A Short Cut to Mushrooms', 'A Conspiracy Unmasked', 'The Old Forest', 'In the House of Tom Bombadil', and 'Fog on the Barrow-downs'. These chapters relate the adventures of the hobbits on their journey through the woods and fields of the Eastfarthing to their eventual return to the main road near the village of Bree. They include the dinner at the house of Farmer Maggot, the revealing of the conspiracy of the hobbits to prevent Frodo from leaving on his own, their adventures in the Old Forest including their encounter with Old Man Willow, their brief stay with Tom Bombadil and Goldberry, and their capture by the Barrow-wight and subsequent rescue by Tom. Although these chapters are some of the most fanciful, their inclusion in the screenplay was not necessary to the story and would have extended the length of an already very long movie.
- In the movie at Bree, Strider is shown drawing a sword that is in one piece. In the book, he bore the shards of Narsil that had been broken when Sauron had been defeated at the end of the Second Age.
- Having not been captured by the Barrow-wight in the movie, where they had obtained their weapons in the book, some means of arming the hobbits had to be devised. This was accomplished by Aragorn suddenly appearing without explanation with four, conveniently hobbit-sized blades that were given them at Amon Sûl (Weathertop). In the book, however, these sword were both terrifying and deadly to the Nazgul, while in the film they had no apparent effect.
- In the book when Frodo is stabbed by the Witch-King with the Morgul Blade, he blacks out and wakes up feeling weak, but is generally capable of speaking and engaging with the others as he normally would, even making jokes on occasion to attempt to lighten the other hobbits' mood. He only gets weaker and weaker very gradually. In the movie, Frodo's reaction to the Morgul-Blade is almost immediate and much more dramatic - he is crippled with pain from the moment he is wounded, and soon becomes deathly sick, pale, delirious and barely alive very quickly, being completely unable to speak or engage with others.
- In the movie, Aragorn also drives off the Nazgul using a torch and a sword, after Frodo drops his own sword and trips over his own feet prior to being stabbed. In the book, events unfold quite differently: Frodo tries to stab the Witch-king with the sword that Bombadil gave him, while crying out the name of Elbereth, which causes the Nazgul great pain; and the Witch-king misses Frodo's heart with the morgul-knife because of this. The Nazgul then flee and do not return, because these things cause them to believe that Frodo defeated the Barrow Wight (it was actually Bombadil) and was in league with the High Elves due to the name "Elbereth" (which he learned from Gildor's company). This causes the Nazgul to fear Frodo, particularly since Frodo's sword was deadly to them. Aragorn simply helps drive them off with two torches after Frodo is stabbed, and they were already retreating; however Aragorn does not understand why the Nazgul did not return.
- In the movie it was Arwen and not Glorfindel who came to rescue Strider and the hobbits from the Nazgul. Arwen also raises the river against the Nazgul in the film, while in the book it was Elrond, using the power of the Elf-Ring Vilya, and Gandalf used his magic to cause the the river to take the form of white horses. Likewise, Frodo rides across the river alone, he is not carried by anyone; and he defies the Nazgul to the end, calling on both Elbereth and Luthien.
- In the movie, the sword Narsil, which is first shown at Rivendell instead of Bree, was in six pieces. In the book, the sword had been broken into two pieces which Aragorn always carried with him.
- The uruk Lurtz who mortally wounds Boromir and is killed by Aragorn does not exist in the book. Rather, Boromir is killed by over 100 Uruk-hai led by a chieftain named Ugluk, who were able to kill Boromir chiefly because he was trying to defend Merry and Pippin.
- Many stories of what was going on in the world were taken out of the Council of Elrond, which included Legolas telling of Gollum's escape, Gloin telling of the messenger from Mordor, Aragorn telling of his capture of Gollum, Gandalf revealing Saruman's treachery, and Bilbo and Gandalf telling the history of the Ring. The last two weren't necessary in the film's version of the council because they had already been told earlier in visual format, however it is unclear why Bilbo, a ring-bearer himself was excluded from the council in the movie.
- In the film, the Council tells Boromir that they cannot use the Ring because it only answers to Sauron; in the book, the Council explains that they can use the Ring, but that it would simply corrupt whoever used it into becoming as evil as Sauron. Gandalf also tells Saruman that only Sauron can bend the Ring to his will.
- In the film, when Frodo shows Bilbo the Ring, Bilbo actually turns into an orc-creature and tries to grab for it; in the book, Frodo only perceives this due to the Ring's influence.
- In the film, Saruman causes the blizzard at Caradhras using a spell; in the book, the mountain Caradhras is a living thing with a mind of its own, and itself causes the blizzard because it hated trespassers.
- At the Hollin Gate: in the book only Sam helps Frodo from the Watcher in the Water, while the others are frozen in fear. Likewise the Watcher does not tear the gates down, but simply closes them and piles up dirt and trees against them, sealing them in.
- When the Fellowship stops in the Chamber of Mazarbul, Pippin accidentally allows a dead dwarf to fall into a well, alerting the orcs to the presence of the Fellowship. In the books, Pippin throws a rock into the well.
- When the Fellowship were at the Gates of Moria, Merry and Pippin threw rocks in to the water and they were stopped by Aragorn. In the books, Boromir threw a rock and Frodo scolds him for it.
- There are many minor (and major) dialogue differences between book and movie. One is that on the Bridge of Khazad-dûm, Gandalf shouts "You shall not pass!" in the movies, which is an order; while in the books he shouts "You cannot pass!" which is a statement. Also in the movie the Balrog seems to easily take on Gandalf, while in the books when Gandalf tells his real identity to Durin's Bane the balrog shrinks from Gandalf, but its shadow grows.
- In the film, Gandalf also breaks the bridge when the balrog advances, in order to stop it; but in the book Gandalf breaks the bridge only because Aragorn and Boromir rally to his aid against the balrog, forcing Gandalf to break the bridge in order to protect them from it.
- In the films, Shadowfax is first introduced in The Two Towers. However, after Gwaihir saves Gandalf from Isengard, he bears him to Rohan where he requests a horse. Theoden agrees, so long as the steed is returned to Rohan. Gandalf chooses the Prince of Horses, who had never been tamed, and was able to do so.
- The quote "don't you leave him" directed at Sam in the film was said by Gandalf. However, in the book, it was an Elf named Gildor, the leader of the company of Elves that Frodo, Sam, and Pippin stayed with for one night in their journey from the Shire.
- The afore-mentioned company of Elves were actually shown in the books, and had interactions with the Hobbits, and they played harps. Their singing had scared away a Wraith that was close behind the Hobbits at the time, as well. In the film, they are merely shown in procession, singing the song shown in the book in Elvish but carrying lanterns.
Much too could be said of his decision to leave out powerful scenes from the chapters Journey in the Dark, The Mines of Moria, The Bridge of Khazad Dum, Lothlorien, and the Mirror of Galadriel.
Naming all the unmistakably important passages present in the book, yet glaringly and obviously missing from the Movie would be time consuming.