I've been looking for a while now, trying to find some sort of boss monster mod. but I haven't found much at all. The only things I've found are "Here There Be Monsters" and various combat overhauls. Skyrim has a lot of pseudo-bosses but I'd like to see a true boss. Something rare that if you have the misfortune to come upon you go "I'm probably screwed, but I'm going to try anyway because if by some miracle I kill it I'll be rich". Do you all (whoever's reading this) get what I mean?

I haven't played any mods other than the Dawnguard & Dragonborn add-ons. If you make it to level 80 in the main game, the Ebony Knight invites you to face him at the Last Vigil. He's very tough to beat. If you play Dragonborn, on Solsteim you will find that the frost giant Karstag is very hard to beat. At level 78 in the main game, Legendary dragons have a shout that takes you down pretty quickly, just when you were getting cocky.

Is that what you were looking for?