This is a mountain that plays a role in J.R.R. Tolkien's Lord of the Rings.
Location: The central regions of the Misty Mountains, above the mines of Khazad-dûm
Passes: The Redhorn Pass
Pronunciation: ka'-rath-ras ('th' as in 'rather')
Meaning: Literally 'red horn'
Other Names: Baraz, Barazinbar, Redhorn
Titles: The Cruel
'...Caradhras rose before them, a mighty peak, tipped with snow like silver, but with sheer naked sides, dull red as if stained by blood.'
The Fellowship of the Ring II 3, "The Ring Goes South "
After the Gap of Rohan was shown to be watched by the spies of Saruman, particularly by intelligent crows or ravens called Crebain from nearby Dunland, the options for the Fellowship's continued eastward movement dwindled to two. This mountain's pass was the last hope of Gandalf for crossing the Misty Mountains while avoiding the horror he was sure lived deep within Khazad-dûm. The section of the Misty Mountains in which it sits rises over the nearby dwarvish capital of Dwarrowdelf, better known as the Mines of Moria. He heard rumor that the dwarves of Moria dug too deep and awoke an ancient evil. But would the mountain let them pass?
Cuiva nwalca Carnirassë! Nai yarvaxëa rasselya taltuva ñotto-carinnar! (Wake up cruel Redhorn! May your blood-stained horn shall fall upon the enemy-heads.) -- Saruman's spell against the Fellowship, from The Fellowship of the Ring movie
Losto Caradhras, sedho, hodo, nuitho i 'ruith! (Sleep Caradhras, be still, lie still, hold your wrath!) -- Gandalf's response
The Fellowship of the Ring movie differs slightly from the book in how it deals with the difficulties the mountain presented. In the movie, it is explicitly shown that Saruman was attacking them, using the weather and the mountain as weapons, causing avalanches and the like. Saruman seems to want to drive the Fellowship into the Mines, for he too knows what lurks and waits. In the book, Gandalf suspects that some powerful will was working against them but is not sure whether the malice was coming from Saruman, Sauron, or some other power.
Sources:
The Encyclopedia of Arda (http://www.glyphweb.com/arda/)
The Lord of the Rings
Elvish and elvish tranlation of movie quotes taken from "Languages in the Lord of the Rings Movies" (http://www.elvish.org/gwaith/movie_elvish.htm). Thanks to nine9 for the info.