A LOTR character: Legolas
A Hobbit character: Lobelia Sackville-Baggins
A place in Middle-Earth: Lossarnach
Things from LOTR: lembas
Beasts/Monsters: lómilendi (does that count as "beasts"?)
A Silmarillion character: Lalaith
Another Barrow Downer: Lalaith
Actor from LOTR movies: b
Lasphemy!!!
A weapon: hmm. I can't think of one right now, though I am sure some would exist. "Longbow" probably won't do. Or "Legolas' bow".
A dwarven character: Lóni
An elf: Lindir