Chicken Pox can cause death in some cases and mostly in adults who's immune systems are compromised or chicken pox can also complicate other problems such as Pneumonia, heart problems and any other serious illness.
Death from Chicken Pox is rare though.
You can get you or child a chicken pox vaccine which is known to kill off other viruses as well but usually chicken pox is nothing to worry about and goes away on it's own within a week or two.