Any famous portrait artists? Urgent..?

You seem to have plenty of artists already on your list. If you want something different to impress, why don't you research Portraiture in Roman art (sculpture) This is an amazing subject, particularly if you look at the sculptures of women - where one can tell from their hairstyles almost the exact date, since styles changed according to period. As for portraiture in general, the book you should get is Roman Art - A Modern Survey of the Art of Imperial Rome by George M.A. Hanfman - it gives all the most famous examples of Roman sculptural portraits and excellent descriptions of each work.