: Morgoth
: Sauron
: Balrogs
: Dragons
: the Watcher at Moria
: them flying things the Nazgul rode
: trolls
: giants
: orcs
: hobbits

Depends on the way you clasify them.
In strength there is no doubt that dragons and balrogs are the worst.
On army job orcs.
Heralds and captains the nazgul and balrogs then again.
The big boss is, of course Morgoth, and later Sauron.
And I don´t think hobbits qualify for any category.

The watcher of Moria is dangerous only if you go near, so, it lacks power for very slow motion.

In my opinion the biggest, baddest monster is Morgoth. The brain that moves all the other pieces (except hobbits, wich are one of the free peoples).

Beren Meldon Nárondorello