Is HSV 1 simplex 1 dangerous can it kill you?

ok i just wanted to know if simplex 1 is deadly? i keep reading that it isnt but then there are sites that say it can by getting to your brain...can somone give me all the right info and is ti possible to get into the brain and kill you if it does get into it is it treatable how can it be diagnosed...just curious cuz i keep reading all this different kinds stuff about it