Who is Sauron?

Painting by Angus McBride

Sauron is a spirit a Maiar one of the lesser spirits that followed the fourteen Valar to Arda (the world) after it was created to give it order and combat the evils of Melkor. The Maiar where also call "the people of" as each of the fourteen Valar had a host of lesser spirits "their people" through which to work their will. Though these creatures were spirits many of them had the ability to take a physical form or had a permeate physical form.

  Painting by Angus McBride

Sauron was the mightiest of the people of Aule the Smith, the Valar of rock and metal who was also the creator of the Dwarves. Melkor did not have a host of spirits who followed him so he recruited followers from the peoples of the other Valar. Sauron became Melkor's greatest follower and chief lieutenant greater even than Gothmog Lord of Balrogs cheif of Melkor's bodyguard. Sauron as the mightiest of the Maiar had the ability to change his shape the shapes he took in the stories were of the forms of a great serpent, a werewolf, a vampire during his titanic battle with Huan the hound of Valinor in the First Age and a fair seeming elf to fool the elves of Eregion during the Second Age. In the Third Age he had lost  his ability to change forms due to the power he lost when he lost the One Ring. The only shape he could muster was that of a great lidless eye. That is the  shape he has during the War of the Ring. As greatest of the people of Aule he had the ability to make things of great power like the Rings of Power and the mighty fortress of Barad-dûr. As the greatest of the followers of Melkor he had the ability fashion creatures of evil he created or improved upon many of the evil creatures that appear in the LOTR trilogy such as, werewolves, half-trolls, Olog-hai, Uruk-hai and the Nazgul. 

Finding the right figure to represent him may seem at first to be a difficult task but he still has his shape shifting ability during the Second Age and his most common shape was that of a "Dark Wizard" so a suitable 15mm figure shouldn't be impossible. Who knows I might even get several different Sauron figures for this game just for the Hell of it.