Gimli, son of Glóin was born in 2879 in the Third Age in the Lonely Mountains. Physically, Gimli was similar to most dwarves, with long brown hair and a flowing, proudly-dwarven beard which was the source of some humor to some his companions. In the year 3018, Gimli accompanied Glóin to Rivendell to represent the dwarves in Elrond's council.* (Glóin, of course, was the companion of Bilbo Baggins on his adventures some sixty years prior.)
After two months, Gimli was chosen to accompany Frodo Baggins to Mount Doom so that the One Ring could be finally destroyed. With everyone's assent, Gimli joined The Fellowship of the Ring. The next morning, the party set out on a treacherous path to Mount Doom. On the way, Gimli and the elf Legolas had their share of arguments, being that both races despised each other. After guiding the Fellowship through the mines of Moria, Gimli became the first dwarf to enter Lorien since the times of Dúrin. He was left with Aragorn and Legolas after the Fellowship crumbled and Frodo and Samwise Gamgee took off on their own.
The three, instead, set off to find Meriadoc Brandybuck and Peregrin Took, the hobbits that were kidnapped just before Frodo and Sam took off. Merry and Pip eventually manage to free themselves and the dwarf stays around with Aragorn and joins the Forces of the West under the command of Aragorn. While Gimli enjoys a great victory over the armies of Sauron with the armies, members of the Fellowship head off to Mount Doom for a final assault to destroy the ring. The ring is eventually destroyed and all the companions are hailed as heroes in Middle Earth. Gimli attends both the coronation and wedding of Aragorn and Arwen.
By the end of the War of the Ring, Gimli and Legolas had overcome their mutual dislike and became the best of friends. Gimli is given the names Elf-Friend and Lock-Bearer by the elves, and all called him the Lord of the Glittering Caves. He journeys through the land with Legolas. Gimli also lead an expedition of dwarves to reconstruct the gates of Gondor with mithril and steel. When Aragorn died in the year 120 of the Fourth Age, Gimli and Legolas sailed over the ocean to Valinor in a ship; Gimli was the first of his kind to see Valinor.
Played by John Rhys-Davies in the movie series.
From The Lord of the Rings by J.R.R. Tolkien
* Several important notes about the first paragraph, after a conversation with DerekL. First, it can be inferred that Gimli does indeed have the description I gave him in the second line, but we don't know it for fact - I guess I went by the movie here, but the books never stated this. The first line is mostly from online sources (www.theonering.net among others) but DerekL cannot find any confirmation for this in the books. I do believe that it is correct and that the information is available somewhere in the indices to the trilogy, but I would not know where to begin.
On the matter of Gimli and Elrond's council, agazade provided some evidence that the dwarves came on their own volition; they did not answer a summons. "And so I have been sent at last by Dáin to warn Bilbo that he is sought by the Enemy, and to learn, if may be, why he desires this ring, this least of rings" (Chapter 3). But it was Elrond who chose Gimli as a member of the Fellowship; he only volunteered in the movie. agazade also points out that Gimli's beard was a subject of humor only in the movie, not in the books.
So I believe what I have up now is correct. Of course, I could be sadly mistaken, in which case you should whip out your Tolkien novels, spend hours looking over them, and /msg me and tell me how much I suck =). My thanks to both DerekL and agazade for their assistance and courteous advice (it would be entirely too easy to get mad at me on account of Tolkien blasphemy). Gracias.