With the amount of people stating they are vampires and immortals and the sort that do not die. I feel pity for them. First of all in the first paragraph I will explain the scientific reasons of death. In the second I shall explain my religions explanation, hence I say my religion the topic may be different for all viewers so afterwards share your belief on. The afterlife.
One must truly understand that without death there would be no life, that if you knew you were never going to die Then why do anything leave it and say I'll do that In a year? It's when the heart stops producing as many blood cells and you become more immune to flus,colds and viruses death is the mirror of life.
So why in the name of the nameless divine would you want to be a vampire, your skin all wrinkly.
In my religion, once death has come your spirit leaves your body. You are then gathered in a boat with all the other spirits that died on the same day as you and ferried across the waters and fogs of kaäl ta mishuu. The great sea once you reach the other side you are judged by the sentinel of souls who judges what you did when you were alive in the physical, the sentinel either shows you the path to the divines home or spirit work, when you spirit work you pay off your debts to the people you have wronged, you give them luck and you guide them you must do this to their descendants and their descendants until three millennia strikes then you are offered again to the sentinel and judged. If you pass you get a seat with the divine.
So I think the vampires have a problem if they do not wish to experience this.