As it is with every book-to-movie adaptation that's ever been done, some of the details about individual characters in The Lord of the Rings were lost in the translation. Gollum is one of those complex characters that could be either good or bad depending on how he's viewed, and Tolkien constructs him as a personification of a moral dilemma. Can a traitor be redeemed, or can a broken person be made whole? That message comes through in the movies, but it doesn't tell the viewer much about Gollum's backstory.
Gandalf, who fills in to dump exposition when he's not being a badass wizard, explains the key moments of Gollum's past in the books, and we see these in flashback scenes in the film. Those who have read the books learn more about this sad, repulsive, and frustrating character and how he came to be what he was by the time Bilbo met him.
6 A Stoor Hobbit
In early Middle-earth history, there were three distinct types of hobbits; Harfoots, Fallohides, and Stoors. Gollum was formerly a Stoor, and these were the Hobbits that lived in the low and fertile valley of the Anduin River. It was the natural place for the ring to end up after being washed down from where Isildur fell, and it wasn't exactly the first time Smeagol and Deagol had gone fishing.
After Gollum killed his cousin, he was exiled and found a home in some dreary caves. By the time he emerged from the depths of the Misty Mountains to pursue Bilbo Baggins and his precious, it was almost 600 years later, and his people were either long gone or extinct.
5 The Gladden Fields
Isildur chose his own fate, and it was unwise to trust the treacherous ring. The place where he fell in the Anduin River was part of a region called the Gladden Fields, and this area is important but never mentioned in the movie. Anyone who was looking for the ring always started here, in the place where Isildur fell.
At the time when Smeagol and his matriarchal society were still living here, most of the other Hobbit tribes had already moved west. These areas that would eventually be settled as Buckland and the Shire, and by the time of the War of the Ring, Hobbits had left the Gladden Fields entirely.
4 Was A Harmless Trickster In Early Version
Tolkien originally intended for Gollum to be more of a benign character, similar to Tom Bombadil, in the sense that he might be troublesome with riddle games or mean-spirited tricks but not dangerous. In fact, Gollum first offered the ring to Bilbo as a prize for winning a riddle game with him in an early version of the story, so there was a time when he wasn't bound to the ring at all.
In later edits, Tolkien not only changed the nature of the ring, but also the character of Gollum. His size also needed to be specified, with early illustrators often interpreting him as a hulking troll or sea monster. Tolkien's description of "frog-like" made him smaller and also explains the animated depictions of him as green and low to the ground.
3 Made Friends With Shelob
If you can call it friendship, although this was really more like worship, and Tolkien has the time and space to go into this sordid relationship with more detail. Gollum made his acquaintance with Shelob well before tracking down Frodo and Sam, and in a bit of credit to what cleverness he had left, he was able to placate Shelob rather than be devoured by her.
In the book, Gollum's plan was simply to lead Frodo to Shelob, where he would be eaten, and Gollum would wait until she was done to retrieve the ring. In the book, however, Gollum actually made a deal with this descendant of Ungoliant, to bring her fresh meat in exchange for keeping the ring.
2 Also Ate Small Goblins
It's not explicit in the movies, and by the look of Gollum he certainly doesn't eat very much, so no further information is required. In the book, however, the reader gets some extra information about how Gollum lives, and it gets a lot worse than raw fish.
Remember, there's a whole community of Orcs and Goblins living in this mountain, and they can get lost as easily as Bilbo did. Occasionally, some unlucky goblin of a smaller size would wander down into the bowels of the mountain and never be seen again. Gollum didn't deliberately stalk or hunt these unfortunate creatures, and he didn't attack Orcs because they were too big, but knowing that he was still capable of wanton murder makes him all the more dangerous.
1 Hates Elves And Everything They Make
It's obvious in the movies that Gollum can't stand the rope that Frodo and Sam tie around his neck, and in the book, he wasn't any quieter about it even though it was tied around his ankle. Tolkien never explains exactly why, but the idea seems to be that what the Elves make is inherently good and contrary to Gollum's duplicity.
It's not because he hates the rope itself. It's an Elvish rope, and anything of Elvish origin causes him intense pain. When he says that "it burns" it's not just an expression. This is also the reason he doesn't eat the lembas bread. It's not as simple as a personal prejudice, the stuff actually hurts him just to be near it.