[Morthoron]

Originally Posted by Mithadan

Boldog, as a name at least, appears early on as a great captain of the Orcs, if I recall. I just finished both Beren and Luthien and The Fall of Gondolin and I took note of a mention that Boldog was slain. If I had to guess based upon memory, I would say it was in the Lay of Leithien.

It is not clear that the breeding of Orcs began after the fall of Utumno. This would mean that the task was left in other hands (Sauron perhaps) or that the breeding began after Morgoth returned to Angband, leaving too little time, in my opinion, to create the armies described in the Silmarillion. Because the corruption of Orcs (and I will not be dragged into the Elves/Men/Beasts discussion) is clearly attributed to Morgoth, I would guess that the breeding program at least began while he was still in Utumno.

While Maiar were clearly recruited by Morgoth, their numbers are not clear. Certainly the Balrogs (hundreds per the Lay of Leithien, seven per later notes), and probably all speaking monsters including dragons, Draugluin and Carcharoth.

As with all things Tolkien, he is variable and obscurant (and probably by design).

Melkor had corrupted many spirits — some great as Sauron, or less as Balrogs. The least could have been primitive Orcs (and much more powerful and perilous) Orcs... (Author's note to text, Chapter 5: "Myths transformed")

This statement by Tolkien aligns with the other matter Huinesoron quoted:

Some of these things may have been delusions and phantoms but some were no doubt shapes taken by the servants of Melkor, mocking and degrading the very forms of the children. For Melkor had in his service great numbers of Maiar, who had the power, as their Master, of taking visible and tangible shape in Arda.('Morgoth's Ring', Chapter 5: "Myths transformed")

Boldog, for instance, is a name that occurs many times in the tales of the War. But it is possible that Boldog was not a personal name, and either a title, or else the name of a kind of creature: the Orc-formed Maiar, only less formidable than the Balrogs. (Author's footnote to the text, Chapter 5: "Myths transformed")

But per usual, Tolkien relies more on inference than direct declarative statements. "Could have been", May have been", "But it is possible" -- one never gets a straight answer. And that's what makes Tolkien lore so intriguing. Conjecture is interwoven with historical background throughout the lore.