Do NPCs recover in the game? (Fallout 3)

NPCs are enemies with the exception of named ones respawn.
A day in three in my opinion. Look for a mod for a fast resp.
ah yes-super mutant hippopotamus does not respawn

you can revive any npc or with the console command resurrect

well, it pleases)) and then a friend told me that he had killed and did not appear again))) I thought the khan would have to start a new save)

They are restored, except for some (For example: Kharya, Jericho, Super Mutant Behemoth, and so on)