[nobody]

I think Gothmog should have been a black Númenórean or at least an uruk, but not a mere snaga. He could not have been a ringwraith as I think in Unfinished Tales it says that all the Nazgûl except the Witchking were confused and disoriented in daylight, especially Khamûl. The movie battle never had any sky darkening or anything, so he should have been a Black Númenórean.