How to kill people who are still alive when brought down to zero health? [duplicate]
For example, Jarl Balgruuf the Greater. I have hit him several times and he still lives.
Solution 1:
Some NPCs are marked as "essential" and can't be killed, but will get back up after kneeling down from their wounds. This is done because killing these NPCs would disrupt the lore and the game's story and quests. Some NPCs will stop being essential after certain quests or milestones, typically after their presence is no longer required for quests.
Jarl Balgruuf is one such NPC and is marked as essential, so you cannot kill him.