The Mouth of Sauron
In the movies we only saw the Mouth of Sauron once and we certainly never heard him referenced by his name. In actuality “The Mouth of Sauron” actually speaks directly to Sauron and is one of the truly evil characters in the book. He is a thorn in the side of the Fellowship in the books—especially Aragorn.
In the books, it isn’t Arwen that saves Frodo from the Witch King in the Fellowship of the Ring. It’s actually Glorfindel. Glorindel arrives just in time to take Frodo to safety after defeating the Witch King on his own. He is also notable for making the prediction that no mortal man would ever kill the Witch King.
Ungoliant is the mother of Shelob the Spider. If you thought Shelob was a big creepy-crawly, you need to see Ungoliant. In actuality, Ungoliant isn’t even a spider— she’s actually a spirit taking the form of a spider. In the end, it took an army of Balrogs to kill her. She was that badass.
Beorn is a giant of a man who had the unique ability of being able to turn into a bear at will. Beorn was actually driven from his home when his homeland was overrun by orcs—he was living as a hermit when he met Bilbo and his fellow travellers in the Hobbit.
Tom Bombadil meets Frodo and the other hobbits in the old forest near the beginning of their journey with the ring. Tom saves the life of Merry after Merry is caught inside a living tree. Tom sings, and the tree eventually releases him. When Frodo lets Tom wear the Ring, it has no effect on Tom—the ring has no power over him.
Later, he saves the hobbits from a bunch of barrow Wights and is later proposed by the Council of Elrond to be the keeper of the ring. Gandalf stands against this idea as he believes Bombadil would see no reason to protect it and may lose the ring.