From this thread I have deduced that:
- Gothmog may or may not have been an orc or a Ringwraith.
- Gothmog may or may not be in some way, shape or form a reincarnation of the spirit of Gothmog Lord of Balrogs.
- JRR Tolkien did not wish for anyone to know who or what Gothmog was, or at least did not care enough about the character to write anything further on the subject.
I ask you, can any more be deduced?