User blog comment:Blood Reaper/Todd Howard Hinting at Future DLC's and Patches/@comment-109.156.46.28-20120223191007/@comment-96.242.7.245-20120225011224

Mehrunes Dagon. They could do a whole "Dante's Inferno" type DLC where you go through all the planes of Oblivion to fight Dagon as he tries to return to the normal world again.