First off, please excuse my ignorance here since I am a "new" Star Wars fan. This is what I know so far. I've read all the KOTOR books, well, except for Red Harvest, of which I am reading now. I also been looking through the Wookiepedia entries as well. From what I can gather the Emperor appears to be Vitiate as he is the only person who was referred to as an Emperor in the KOTOR timeline. It was also mentioned that eventually he was overthrown by the Dark Council, of which turns into the Brotherhood of Darkness and subsequently destroyed by Darth Bane.