I was curious to know how he looked like without his mask, so I found him on Creation Kit, removed his inventory, preview, and voila - Miraak looks plain human(about 55 years old), but, he also has full black demon eyes(MaleEyesHumanDemon). Also, on the traits tab it says "Race: NordRace", proving Miraak is an actual Nord without an specific "MiraakRace" as some people were saying. I couldn't find any thread about that so I thought it would be interesting for those playing Dragonborn to know more about Miraak.