Nez'ra

Nez'ra was a demon prince. His horns are powerful artifacts stolen many years ago from Ravenholdt Manor by the Blackrock clan.

Speculation
Since the horns were stolen "many years" before the events of World of Warcraft, the theft might have happened during the Second War, when the Old Horde invaded Lordaeron, or during the Third War, when a demon-worshiping part of the clan was still in the vicinity of the manor.