King Sombra

King Sombra is a villian introduced in the season 3 premire of MLP:FIM, he is protrayed as the former ruler of the Crystal Empire

Deceptiocns in Fan labor
With what little lines he had during his breif role, his fate is left undecided in the canon, is most fanfiction he is either dead or survives his ordeal he makes a suprising return the exact his revenge on the main six and Celestia and Luna and tries to take over the Crystal Empire and ultimatly Equestria. Very little fan labor protrays him as a hero or having redeming qualities

Shipping
In most fanics he is shipping with Celestia, Luna, Queen Chrysalis and in some cases Twilight Sparkle in stories Kiss of the Dark and His Black Hearts Inquiry