The creature Gothmog at the Siege of Minas Tirith

[obloquy]

Originally Posted by narfforc

Readers suggestions that the later Gothmog was a Nazgul or a Black Numenorean are no more than speculation; in the absence of further detail by Tolkien.
It is not clear if lieutenant here means the second-in-command of Minas Morgul or, more likely, second-in-command to the Witch-king, who is sometimes called the Morgul-lord. (Hammond/Scull)

Why is the latter more likely? The Witch-King was never called Morgul. It seems more likely to me that lieutenant of Morgul should be taken to mean lieutenant of Morgul. Actually, why does it matter which is intended? Both would almost certainly be positions reserved for Nazgul.

The assumption that the second-in-command on the Pelennor was a Nazgul is a fairly reasonable one.