I always thought it would be cool to encounter and fight hostile werewolves on a full moon...
I downloaded a mod that makes the encounters more 'frequent' apparently.
I never experienced any in the vanilla game + DLC
They do if you have dawnguard but they are very rare and mostly happen around the rift aria. The Moonlight tales mod makes them more frequent.
It's happened for me, of course, I have both DLC expansions, but they are usually pretty easy with a good armor rating. If you aren't on a mountain, of course...
DO NOT FIGHT THEM ON A HORSE! Or on a mountain/high cliffs, as they do have many knockdown moves. They are also fairly easy with a shield-wielding build.
I would recommend any shouts/spells that knock them down, as they attack quite fast and are very hard to stagger.
They sometimes fight like the Greybeards, by keeping you knocked down and ripping you apart while you are on the ground.
Slow casting spells are NOT recommended, but i would recommend these: Slow poisons, Ice Form (Any words), Unrelenting Force (Word 3/3 Dah), Cyclone (DB), Stamina poisons, Frost spells/enchantments, Any really strong stagger (eg, Unrelenting force word 1-2/3 Fus, Ro. Or Shield Bash abilities)
In some extremely rare cases you may wait so long that they will revert back to human form before death. This most commonly happens when you become undetected, but they may revert back to were-form when you get detected again.
They may knock you down by roaring.
Most of these (If not all) also apply to were-bears (DB).
I′ve seen werewolves with the name tag Farmer, although I′ve never seen them changing. Happens a lot while I′m chasing dragons in the wild, I suppose the dragon attacks the farmers and they turn.
Extremely rare encounter for me but it was pretty epic as well. I was minding my own business near Treva's Watch when i saw 3 black figures running towards me and eradicating some elks along their way. I don't usually fear in Skyrim as i know the game pretty well nowadays but this encounter gave me the chills. Not only that but they forced me to use potions to keep up, something that i do only when i absolutely have no other choice. Epic encounter.