A LOTR character: Tom Bombadil
A character from The Hobbit: Thranduil
A place in Middle-Earth: Tuckborough
Things from LOTR: trees
Beasts/Monsters: trolls
A Silmarillion character: Thuringwethil
Another Barrow Downer: Taralphiel
Actor from LOTR movies: Tyler, Liv
A weapon: *head explodes because can only think of weapons in Finnish* throwing dagger?
A dwarven character: Thorin Oakenshield (in Finnish, he would have even two T's
)
An elf: Thingol
A hobbit: Ted Sandyman
A human: Théoden
An elf-human hybrid: Tar-Elros
A maia: Tilion
A place in Aman (including Tol Eressea): Tol Eressea