eschatology
Eschatology is the branch of theology that deals with "last things," whether the death of an individual or the decline of humanity, or the end of the universe itself. Ideas about heaven and hell fall under the category of eschatology, as does belief in reincarnation.
Eschatological beliefs about the end of the world, or of humanity's role in it, vary widely across religious traditions, from the end-time scenarios of contemporary evangelical movements to Hindu ideas about the great cycle of epochs, or yugas, to the Buddhist belief in the coming of Maitreya.
The word comes from the Greek, eschatos, meaning "last."