10 Video Game NPCs You Should NEVER Kill
2. Yagrum Bagarn - Elder Scrolls III: Morrowind
Before Skyrim made characters indestructible, Morrowind decided to let players eat their cake and suffer with the consequences. That is to say, every NPC in the Elder Scrolls III is technically killable. You will, with a great many of the most important ones, receive a prompt that warns you that what you did has had a profound effect and "severed the thread of prophecy", recommending reloading a save.
But you don't technically have to and, in all fairness, it's still possible to complete the game no matter what you do or who you kill... with the exception of one character.
Yagrum Bagran is the last living Dwemer and a key figure in the game's story with how it relates to defeating Dagoth Ur. He's the only person in Morrowind with the knowledge and skill to restore the power of the Wraithguard, which is a necessary tool in taking down the immortal final boss of the game. The gauntlet itself is a gift from Vivec but, thanks to a sneaky and exceptionally hidden "back path" route, it's possible to get Wraithguard by killing the NPC.
In fact, the back path method is a totally viable option if you want to roleplay as a sociopath on a killing spree... you just can't murder Yagrum and expect to finish the game. Lucky him.