iLouis
Psst...I know who you are. Hail Sithis!
Captain Hargar. The son of a bitch has an insane amount of health and was harder to kill than a giant.
^THIS! Damn, that bastard killed Lydia like 4 times so I kept having to load a save. But definitely, besides the obvious dragon priest or frost troll, Captain Hargar will own you all day.