I want to show my groupmates D&D 4e, but they know nothing about it. However they do know The Lord of the Rings, so I would like to convert the characters from there into D&D 4e.
Any books can be used as a sources, because I'm going to make pregenerated characters for them. But I don't know which classes I should use.
My assumptions:
Frodo - Halfling Rogue
Gimli - Dwarf Fighter
Legolas - Elf Ranger
Aragorn - Human ???
Gandalf - Human(?) Wizard(?)
Pick the classes and races that best capture those characters to you. It seems to me you're having trouble because you want to make sure you do them the right way, but there isn't any one right or best way to do them.
Last year, we broached the topic of how to build Gandalf in D&D 3.5e. BESW summarised the problem with this quite well in his answer:
You want to "recreate Gandalf from the books" "in D&D3.5 terms." You can't, not precisely. D&D isn't a good fit at all for actually recreating LotR scenarios or characters: it has a different mythos, a different philosophy toward magic, and is built with mechanical considerations that Tolkien didn't have to worry about.
The same problem exists for D&D 4e. Since it's so totally different, there's not going to be any single correct or totally accurate way to convert LotR characters to D&D 4e. Instead, there's multiple ways, all of them accurate from certain perspectives. Tolkein also had the leeway to make characters who weren't total fight machines, such as Frodo, so converting them into a system where player characters are all about fighting well is going to take some ingenuity (and might be best avoided as player characters).
The best you can do is as BESW suggested in his answer: consider what the character means to you, and take one perspective on them. Then create a build that captures that perspective on the character quite well.
Gandalf could be a Wizard, or possibly more suitably a Bard. Aragorn may be a melee-focused Ranger, Cleric, Paladin or Warlord. Since you won't find a single correct approach, the important thing is just that it feels right to you, and that your build captures an aspect of that person well.
D&D 4e is also very accommodating of refluffing, since this edition in particular has very well separated mechanics from fluff. You can change the descriptions of items (PHB p224, RC p279) and powers (PHB p55). Class descriptions should be taken as guidelines, race descriptions suggestions of the typical features. This means you can acknowledge Aragorn's half-elven heritage by statting him as an Elf or Half-Elf, and still give him a human appearance and call him human in-game.
While Jonathan Hobbs is definitely correct that there is no one exact build that is going to be correct for each character, I do think there are some general guidelines we can establish: Legolas is Fey, Frodo is a halfling, Aragorn has a sword, and so on.
What you do with those guidelines is going to depend on your own personal take on the character. To make that process more clear, I'll present my personal take on each character along with some other common possibilities.
Frodo
As before, Frodo is clearly a halfling. We can all agree on that.
Beyond his race though, it gets tougher, largely because Frodo isn't really all that heroic. At least in the DnD sense. That being said, I do have a suggestion:
I would focus on Frodo as a stealthy exploration rogue, perhaps with some abilities that let him turn invisible.
Although there are other aspects of the character you could emphasize, I feel that rogue makes the most sense because -- to me -- Frodo's greatest accomplishment was sneaking through Mordor to Mt. Doom. As Brian S pointed out, Frodo is not a Striker rogue. He barely participates in combat at all. Much like Bilbo, Frodo's value lies in being a little halfling. Granted, he may not sneak around quite as much as Bilbo, but as a DnD character he needs to be good at something, and if I tried to make it Mt. Doom in a 4E game, I'm pretty sure I'd make some Stealth checks. It doesn't hurt he has a ring which lets him turn invisible.
If you'd rather emphasize another aspect of the character, you might focus more on his ability to inspire his allies. Perhaps make him a bard or inspiring warlord. Frodo is also known for his ability to resist the ring's seduction and keep his head on straight, so you might focus on giving him a high will defense and fill in the other details as you like.
Gimli
Gimli is a dwarf, of course, and he's going to use Martial abilities.
I would suggest a fighter would probably make the most sense, but warlord wouldn't be unreasonable. If I recall, Gimli used an axe. Don't know that there's much more there.
Legolas
Legolas is Fey, and he's an excellent archer.
I would go Elf rather than Eladrin, as Legolas is from the forest, and elves are better archers than Eladrin. Obviously he's not a Drow. Elrond might be an Eladrin. We all agree Legolas is an archer, as you noted, but he can also fight well with two blades (see the Desolation of Smaug's absurd barrel scene), so a good build would probably include that capability. Hunter rangers are proficient at switching back and forth between melee and ranged combat.
Aragorn
Aragorn is man. He uses swords. He has both nature and leadership skills.
Aragorn does have elf heritage in the distant past (Elrond's brother), but I think the vast majority of people would expect him to be human, rather than half-elf. Additionally, Aragorn is initially introduced as the ranger Strider, not as Aragorn, the heir to a long line of kings. I feel that Strider is the prototypical ranger, and that any build of Aragorn in which he is not a ranger is 'doing it wrong'. That being said, what I really expect is for Aragorn to have good outdoor skills, so even if he's not a ranger he should have high Nature.
Another very logical build of Aragorn would be as a tactical warlord or possibly a paladin. This emphasizes his later role as the king of men over his earlier role as the ranger Strider. Maybe a hybrid?
Gandalf
Gandalf appears human, but he's not technically. He's a wizard, which is a sort of supernatural demi-godish being. He has magical powers, and can effectively wield a sword.
Wizard isn't a race in DnD, but there is a race of reincarnating immortals with great magical power: devas. Ignoring the physical appearance, the description of Devas in the Player's Handbook 2 sounds like a pretty good description of Wizards in LotR to me. You might also reasonably consider many other races, such as human, elf, eladrin, half-elf, a conversion of an old race, or even a home brew.
As Jonathan Hobbs pointed out, Wizards in LotR don't have the same kind of flashy spells that they have in DnD. Some of Gandalf's powers almost seem more Divine than Arcane, so perhaps a Divine class such as Invoker might make more sense. This would be in line with his own nature as a supernatural entity.
Note that Gandalf is effective in melee with both longsword and staff, so the best build would take that into account.
Summary
So there are some pretty general guidelines, along with more specific opinions. You seem like you want a specific suggestion for classes though, so here's a group of builds consistent with both those guidelines and my own opinions:
Frodo: Cunning Sneak Halfing Rogue
Gimli: Dwarf Fighter
Legolas: Hunter-Style Elf Ranger
Aragorn: Two-Blade or Marauder Human Ranger
Gandalf: Malediction or Preserving Deva Invoker
I have a few points of contention with each of the previous answers so I'll supply my own.
Power Level
It is important to note that most of the characters are nowhere near the same effectiveness.
Tier 3: Gimli, Aragorn, Legolas(?) - Dwarf Fighter, Human Warlord, Elf Ranger
Tier 4: Gandalf - No. Just no.
What's with the tiers?
By the time the companions get to Rivendell, Frodo might be level one. The only skills the hobbits really display before Rivendell is hiding. They do things before that but they don't do them effectively. In 3.5 I might give them 1 level of an NPC class.
Boromir shows significantly more ability than the hobbits but still dies in circumstances where each of the other three hold their own. It could just be bad luck but we don't have much else to go on.
Aragorn and the rest are 5 to 10 levels over the hobbits, easily mowing down enemies that the hobbits can only cower from.
We'll get to that line break in a minute...
Not Rogues
Honestly, this one is mostly instinct. In the later parts of LotR, Merry joins the army and Pippen literally becomes the court bard. Even at this point, I probably still wouldn't point them above level 5.
Don't worry, Mr. Frodo.
Samwise Gamgee is literally a walking peptalk. I suppose he could also be a leader class with all the emotional healing he does, but really nothing says dedicated support class quite like Bard. He does, however, demonstrate these abilities much earlier than many of fellows.
Why Paladin?
Despite the amount of temptation we see put on Boromir he remains faithful to his cause. And in the end, despite all the temptation, he does his duty. He is also a very protective character so I think the temperament of the Paladin concept combined with its defender role matches well.
Arwen
We don't really see enough of her to judge her power level but she seems to be a match for Aragorn. I dropped her a tier because she's clearly a support character but she also clearly has the potential to be much, much more. Either way she evidences both blade skills and magic. In 2-3.5, her elf-ness would have handled that and she could have been a straight magic-user. Of course, before 2nd ed, she would have just been an "Elf" and we'd be done with it.
Warlord? Seriously?
Yes, seriously. So, in 3.5 I would have statted Aragorn as a Ranger. He is arguably the very reason the class exists - at least with that name. But 3.5 had a lot more flexibility in terms of specialized classes, advanced classes, and multi-classing. At it's heart, Aragorn's story is not that of a warrior but of a leader coming to terms with what that means. In the books, and more-so in the movies, Aragorn spends a good deal of his time arranging tactics, organizing troops, and even leading armies. Much more than he actually spends in one-on-one or one-on-many engagements. I'd go very heavy on the martial feats to make up for it, but to my mind he's a leader.
Elf, not Eladrin
Don't forget that Legolas is the son of Thranduil who was a Silvan elf and lord of the Woodland Realm. He is also incredibly proficient with a bow and moves easily over unstable terrain. Sounds like an Elf to me.
No. Just no.
Hobbs and Shannon already touched on this but I don't think either went far enough. The problem is that Gandalf isn't just "another race". He is an Ainur, the same sort of entity as the very gods (for D&D purposes, at least) of Middle Earth. He is of the lesser sort, the Maiar, so we can call him a demi-god if you want. He and the other Wizards (more properly Istari), were exactly the same sort of creatures as the Balrog and Sauron himself, though they concealed their nature and power from mortal men. In fact, the only times that Gandalf was ever truly implied to be under threat was when facing one of these beings.
There's a (narrative structure) reason that Gandalf randomly exits the story at various points. He is so far beyond the other characters that if he were to stay with them the whole time there wouldn't have been enough "on-level" challenges for them to experience character development. It might help to think of him leaving as the opposite of a deus ex machina.
So, please... if you insist on including Gandalf in your game, hold to that narrative spirit. Don't make him a PC and don't let him involve himself in the characters' problems beyond offering advice or saving them from problems you put there for narrative reasons instead of meaning the characters to face them.
