[the guy who be short]

The Encyclopedia of Arda claims:

As second-in-command to the Lord of the Nazgûl himself, he clearly had very great authority over Sauron's forces, and this has led some to suggest that Gothmog was also one of the Nazgûl. This by no means impossible, but it is notable that Frodo and Sam, who saw the Witch-king lead his armies from Minas Morgul, only observed one Nazgûl leading the host.

Which is an incredibly good point. Surely the lieutenant of Morgul would... be with the hosts of Minas Morgul? But Frowise only saw one Nazgul, The Witch-King.

Well, that seems concrete to me. I'll just sit and wait for Formendacil to come back and blow gigantic holes in it.