[Nerwen]

A LOTR character: Rosie Cotton
A character from The Hobbit: Roäc
A place in Middle-Earth: Rauros
Things from LOTR: Rings (Gee, that was hard...)
Beasts/Monsters: Rochallor
A Silmarillion character: Rían
Another Barrow Downer: Rikae
Actor from LOTR movies: Rhys-Davies, John.
A weapon: The Red Arrow
A dwarven character: You've got me on that one.
An elf: Rúmil
A hobbit: Rory Brandybuck
A human: Ragnor
An elf-human hybrid: Rómendacil I (yes, I know, it was a long way back.)
A maia: Radagast