Turbine's regular The Lord of the Rings Online Lorebook updates. The Lorebook is essentially a wiki that contains both gameplay information and Middle-earth lore. Some of the entries are made by players, and some are official. They usually focus on a particular character or place that Turbine has extrapolated or expanded from J.R.R. Tolkien's book trilogy.
The North American LotRO site hadn't been updated with any featured Lorebook entries in a while, but a couple new ones have finally arrived. First up is Bolgrukh -- a half-woman, half-bat horror who picks of hapless adventurers near Carn Dum. Apparently she was enslaved by Morgoth, and if you know your Middle-earth lore, you know that makes her really old. And old monsters are usually scarier than young ones!
The second entry is the Rogmul (Balrog slave) Udúnion, a level 52 Nemesis boss who will most certainly annihilate almost everyone he ever sees. He too is extremely old; the entry lists several historical events he's witnessed. And you know something's badass when its classifications are "Ancient Evil" and "Nameless." Fear!