if you kill someone do they come back to life or are they dead foreva?

i knw that there is a staff of worms which brings back recentky deceesed beings for 30 seconds

ps sorry if this is an old topic but i cant find it anywhere

Be more specific.
Do you mean NPCs, such as merchants and other citizens?

Once they are killed, they are gone.
The NPCs who can't die are important/quest NPCs,
which can be told apart from regualr NPCs when you look at 'em.
The talk symbol will be in the shape of a crown.
Unless the quest kills that character off, they will only be "Knocked unconscious."
They will later get up like nothing happened.