We read from SIL "
"for there
Oromë would train his folk and his beasts for the pursuit of the
evil creatures of
Melkor."
.... If Oromë trained beasts for pursuit of Melkors 'evil creatures' then clearly some of those were 'beasts' as well. What kind? Uncertain.
"And Oromë tamer of beasts would ride too at whiles in the darkness of the unlit forests; as a mighty hunter he came with spear and
bow, pursuing to the death
the monsters and fell creatures of the kingdom of Melkor, and his white
horse Nahar shone like silver in
the shadows."
..... what would we put in the category of 'monsters', and would they possibly be 'lesser' than
Orcs? Maybe.
"Therefore an army was sent against him under the command of
Sauron; and Sauron
brought were-wolves, fell beasts inhabited by dreadful spirits that he had imprisoned in their bodies."
"For other
foul creatures of spider form had dwelt there since the days of the delving of
Angband, and she (
Ungoliant) mated with them," (But these spider 'creatures' are later called the 'creatures of Ungoliant rather than of Melkor/
Morgoth.)
....in this case, we can assume these 'foul creatures of spider form' were not of Ungoliant, but were bred during the 'delving of Angband'. Thus we have
Spiders confirmed to be among the corrupted creatures, certainly lesser than Orcs, as they can be fairly easily slain.
"So terrible did he (Carcaroth) become in his madness that
all the creatures of Morgoth that abode in that valley, or were upon any of the
roads that led thither, fled far away;
"From their far
journeys they brought tidings of a great mustering of
Orcs and evil creatures under the eaves of Ered Wethrin and in the Pass of Sirion;"
"‘
There are fell beasts,’ they said, ‘in the land east of the
mountains, and your ancient kindred that dwell there are flying from the
plains to the
hills.’ And ere long the evil creatures came even to
Beleriand, over passes in the mountains, or up from the south through the dark forests.
Wolves there were, or creatures that walked in wolf-shapes, and other fell beings of shadow; and among them were the Orcs,
"Thereafter the thought of Morgoth was bent unceasing on the mountainous land between Anach and the upper waters of Sirion, whither his servants had never passed; yet still
no spy or creature out of Angband could come there because of the vigilance of the
eagles, and Morgoth was thwarted in the fulfilment of his designs."
"But after many years, when well nigh a third of that age of the world had passed, a darkness crept slowly through the wood from the southward, and fear walked there in shadowy glades;
fell beasts came hunting, and cruel and evil creatures laid there their snares. Then the name of the forest was changed and
Mirkwood it was called, for the nightshade lay deep there, and few dared to pass through, save only in the north where
Thranduil’s people still held the evil at bay."
"Many things of beauty and wonder remained on earth in that time, and many things also of evil and dread: Orcs there were and
trolls and
dragons and fell beasts, and
strange creatures old and wise in the woods whose names are forgotten;" (rhis was in the 'fading years' as the age of
Men was preparing.)
We also need to remember
Eru says of the creation of the
Dwarves:
... "‘Why hast thou done this? Why dost thou attempt a thing which thou knowest is beyond thy power and thy authority? For thou hast from me as a gift thy own being only, and no more; and therefore the
creatures of thy hand and mind can live only by that being, moving when thou thinkest to move them, and if thy thought be elsewhere, standing idle. Is that thy desire?’"
And frequently men, Orcs,
Elves etc. are referred to as 'creatures'. So it's entirely possible And we know Melkor and Sauron both corrupted some of all the
races to their service... (except possibly
hobbits, of whom it seems they knew nothing.)
All the above said: we know Melkor corrupted everything created, even the land. So IF there was a creature of any kind... a deer, a bear, a wofl, a rabbit, a bird, anything... he likely corrupted some into his 'fell creatures'.
But of actual specific MENTION, Ent has still found only "wolves" noted to this point.
NOTE: The term "fell" simply means "morally wrong or evil" - so when
Saruman used the
Crebain out of
Fangorn and
Dunland as his spies, he also 'corrupted' and made them "fell creatures" doing his bidding for evil.
Ent's current opinion/conclusion: Morgoth had many 'lesser creatures' of
Mordor in his service of many kinds. But so far, only 'wolves' and 'spiders' are confirmed by name. We can surmise any and many others... but whether they are 'lesser' or 'greater' than Orcs will likely remain a matter of opinion.