Sauron as Annatar. The beauty of him lured the elves and the men in the second age.

I am re-reading Silmarillion and it is damn awesome. There are some badass characters in those books. Lúthien especially. Without her and Huan, Beren would never have been able to get the Silmaril.

Anyway, Sauron in all his forms are one of my fave characters in all the books.