Modder ‘Axarien’ has released a pretty cool mod for The Elder Scrolls V: Skyrim that aims to overhaul over 125 NPCs. As the Axarien noted, this is a unique, vanilla-friendly, high poly appearance mod that improves 125 male and female NPCs.
The mod improves mostly the NPCs of the main game. However, it also covers a few from the Hearthfire, Dawnguard, and Dragonborn DLCs/expansions.
You can download the mod from here. Do note that this mod is for Skyrim Special Edition, and not for the Original/Legacy Edition. Below you can also find screenshots that showcase some of the overhauled NPCs.
Speaking of Skyrim Special Edition, we also suggest checking the following ones. Wyrmstooth is an expansion-sized mod that adds new quests and dungeons. There is also a mod that brings elements from The Witcher games to Bethesda’s RPG. Dragon Hall Tavern is another 2GB DLC-sized mod for Skyrim, adding new quests, locations, arena & more. Then we have Land of Vominhem and Legacy of the Dragonborn. And finally, you should check out this Castlevania-inspired mod, this mod that adds to the game the Nemesis system from Middle-earth: Shadow of Mordor, this DLC-sized Mod that adds six main isles to explore, as well as this sci-fi city fan expansion, Skyrim Together Reborn, and this RTS/City Building Mod.