Giants....

... I believe in the Lord of the Rings we hear of Giants. When Gandalf and the Fellowship were crossing Cadrahdras, (spelling?), in the Misty Mountains, rocks are aimed at our party and there are voices in the air, and Gandalf speaks of creatures that don't serve Sauron. Are these Giants?

[Legate of Amon Lanc]

Possibly. This would be one explanation. The other is, that it would be Caradhras itself: if you take literally Gimli's (and Gandalf's, and whoever else might have said it) lines about "cruel Caradhras". It might be pure personification of the place, but it seems like something more. My thoughts come from these points in the text:

'We cannot go further tonight,' said Boromir. 'Let those call it the wind who will; there are fell voices on the air; and these stones are aimed at us.'
'I do call it the wind,' said Aragorn. 'But that does not make what you say untrue. There are many evil and unfriendly things in the world that have little love for those that go on two legs, and yet are not in league with Sauron, but have purposes of their own. Some have been in this world longer than he.'
'Caradhras was called the Cruel, and had an ill name, said Gimli, 'long years ago, when rumour of Sauron had not been heard in these lands.'
'It matters little who is the enemy, if we cannot beat off his attack; said Gandalf.

Thus, why I think it is Caradhras itself:
1. Aragorn calls it the wind, though he agrees that it is this "wind" what is evil here. It would seem to me as weather around the Caradhras, being something like a part of it.
2. Aragorn speaks about things, which have little love for those that go on two legs. If I am not very much mistaken, then Giants have two legs, then why would they hate everyone who walks two legs. It might be a metaphore that they just hate all living, but why would then Aragorn use such a stupid metaphore, when the Giants have two legs as well.
3. Gandalf has on his own eyes seen Giants (in the Hobbit) and he spoke about them to Dwarves and to Beorn, but he seems reluctant in naming the enemy now (unless he just doesn't want to talk about nonsenses while there are more important things to do). It seems to me that Gandalf does not know who the enemy is, or that it is something he does not want to talk about.

And to end this, for illustration just more quotes from Gimli, which may take Caradhras just as a personification, but also might consider Caradhras as true entity:

'Caradhras has not forgiven us.' he said. 'He has more snow yet to fling at us, if we go on.'
(...)
'It was no ordinary storm. It is the ill will of Caradhras. He does not love Elves and Dwarves, and that drift was laid to cut off our escape.'

It is true that it might be a "strange dwarven belief" (as is mentioned in Appendix A III, that the Dwarves "had many strange tales and beliefs"), and the fact that Boromir says to Gimli "But happily your Caradhras has forgotten that you have Men with you" (which seems to me like a little scoff) would somehow support that. But still, maybe Boromir was the one who didn't know everything about mountains.

[MatthewM]

Great topic, and great post Legate. You pretty much laid it all out there. I myself always thought of the attacks on The Fellowship due to Caradhras itself. All the references point to so, and I would believe like you said that Giants would have two legs...so why would they hate other two leg beings, if there were Giants present at all? Unless we apply Gimli's "belief" into the mix, whereas if there were Giants, they probably wouldn't care whether or not 2 Men were with the company (Boromir's response), if they knew an Elf and a Dwarf were abroad (doubtless the Hobbits would be unknown and also be considered Dwarves to such a folk as Giants would be, therefore increasing the amount of Dwarves.)

But, I think it's safe to say the evil at work here is Caradhras itself, at least in my opinion. Aragorn agrees with Boromir when he confirms calling it the wind.

[Rhod the Red]

Giants assault the travellers in The Hobbit just before the Goblins do, by throwing rocks down.

[The Might]

an interesting topic indeed...
But I don't really know what to think
We know that it is was said that giants had not always lived in the area of the Great Pass, and that the great bears, possible ancestors of Beorn had lived there before their arrival. It could be a possibility that they had migrated north in time.
After the Battle of the Five Armies it is said that the goblins hid themselves and the mountain passes were made safe again, perhaps the giants were forced to return in the southern part of the Misty Mountains.
It could be that because the Dwarves did not know or see the giants they believed that the mountain was against them and attributed such events to supernatural forces, not to normal creatures like giants.

However it is hard to say what Tolkien really thought about, the Hobbit is very different from LOTR.

[Mithalwen]

Possibly some variant on a troll? Pio is the troll expert (they have featured in a couple of RPGs I have played) and not all are light sensitive.