How did one little book become three epic blockbusters? Peter Jackson and company added a few things to J.R.R. Tolkien's original tale to bump up the action and even add a little romance. Here's a rundown of the major changes.

Frodo Baggins wasn't even a twinkle in Tolkien's eye when 'The Hobbit' was published in 1937. Yet Elijah Wood cameos as Frodo in 'An Unexpected Journey’s' flash-forward prologue, along with Ian Holm as the older Bilbo.

The daffy wizard only warrants one fleeting mention in Tolkien's book, when Gandalf refers to him as his "cousin." In the movies, however, Radagast (played by onetime 'Doctor Who' portrayer Sylvester McCoy) sees plenty of action.

This vengeful Orc – one of the main villains in the 'Hobbit' films – isn't even alive in Tolkien's version of the story. According to the author, Azog was slain years earlier by a dwarf named Dain (who appears in 'The Battle of the Five Armies').

Speaking of villains, the Necromancer is only alluded to in the book. It's been said that Tolkien already knew this was Sauron, the future 'Lord of the Rings' antagonist, but his 1937 'Hobbit' readers had no idea of the presence the figure would have in the saga to come.

Sauron reveals himself to Gandalf (Ian McKellen) at his fortress, Dol Guldur, in 'The Desolation of Smaug.' But this scene isn't in the book. Gandalf's encounter with the evil sorcerer is only detailed in the 'Lord of the Rings' appendices.

Tolkien's 'The Hobbit' was essentially an all-male adventure. One of the few female characters in the 'Rings' trilogy was Galadriel, so Jackson brought back Cate Blanchett to reprise her role in scenes written especially for the 'Hobbit' films.

The "White Council" meeting between Gandalf, Elrond (Hugo Weaving), Galadriel and the deluded wizard Saruman (Christopher Lee) is nowhere in the book, because Tolkien didn't introduce Saruman until 'The Lord of the Rings.'

The girls all swooned at Orlando Bloom in the 'Rings' flicks. Perhaps that's why Jackson gave Bloom's character, Legolas, a central role in the second and third 'Hobbit' movies. But is the handsome Elf in Tolkien's 'Hobbit'? Not on your life.

Perhaps the most controversial addition is Evangeline Lilly’s Elven warrior, along with the love triangle she forms with Legolas and the dwarf, Kili (Aidan Turner). Tauriel is entirely the invention of the filmmakers. Tolkien never dreamed her up.

While we're on the subject of the hunky dwarf, the entire subplot of him being wounded by an Orc's arrow, then resting up in Lake-town (and nursed by Tauriel) while his fellow dwarves move on to the Lonely Mountain, exists only in the movies.

As he does in ‘The Fellowship of the Ring,’ Gandalf counts on a messenger moth to alert the Eagles to his and his friends’ predicament in the burning trees. In the book, the Eagles – who can talk – see the smoke from afar, then come to the rescue.

The conclusion of 'The Desolation of Smaug' has Bilbo (Martin Freeman) slipping the Ring on and off as Smaug (Benedict Cumberbatch) pursues him. In the book, he sensibly keeps the Ring on throughout the scene, maintaining his invisibility.

In 'The Desolation of Smaug's' final moments, the dwarves forge a giant statue that nearly drowns Smaug in liquid gold. No such thing happens in the book. Indeed, the dwarves never deal with the dragon. In Tolkien's version, it's just Smaug vs. Bilbo.