Darksiders, Wicked K (Posh Fallen)
This is a very odd encounter i found directly outside of the first boss' castle. You need a weapon thats unlocked well after you finish her so you will have to come back in order to reach it. Just get across (you will know the spot just outside the castle by the time you have this weapon) and he is inside this little cave. Nothing came from the battle, this guy just runs away mid fight, its kind of odd.