TAR-CALION: A rodent scurries backwards, joining A noteless baby cow and a charged atom for him.
HERUCALMO: A pronoun, a state of mind and a vowel reveal him.
B
ILBO: One of the titular characters. Take the second.
M
ELKOR: The limping evil dude. Take the second.
WUL
F: He is lupine with a vowel switch. Take the fourth.
I made a mistake with the clue. I should have said 'two vowels' rather than 'a vowel'.
I also wanted to put in Castamir, but couldn't fit a letter anywhere. The important ones were included, though, so you win some, you lose some. Bilbo and Phary provided the crux of the theme.
Over to
Huey.