If you've hit Skyrim's level-cap and are kind of feeling like the game has no challenges left to offer you, the new Dragonborn DLC has something for you: The Ebony Warrior.
According to a thread at the Bethesda forums, the Ebony Warrior is an extreme B.A. who tracks you down if you've hit level 81. Posters report that he has a 15-second paralyze ability, a resistance to fire, a powerful self-healing spell, and a sword that sucks your health and restores his.
From what everyone over there is saying, he is the hardest enemy in the game by far, and no one has beaten him in their first one-on-one encounter. "Took me 4 attempts," writes user Sh00byD00. "He's like 15 legendary dragons in one."
As much as I'm looking forward to playing Dragonborn on PC, especially given that it sounds like a proper expansion pack, I like this kind of extra stuff that Bethesda packs in to their DLC even more than the main quest. Kind of like the rest of Skyrim, I guess.