Eschatology literally means "the study of last things". It is a general-purpose term that can have more than one meaning. In Zoroastrianism, Christianity and in Norse pagan theology, eschatology refers to a theology concerning the end of the world, as predicted in in the prophecies of these faiths, and as recorded in their sacred texts. Eschatology also refers to the study of general afterlife concepts of other religions, especially the western monotheistic[?] faiths. In this broader sense, eschatology can refer to the messiah, a messianic era, the afterlife, and the soul in religions which have such beliefs.
As far as we know, Zoroastrianism had a fully developed concept of the end of the world as being devoured by fire already in 500 B.C. and is thus the oldest eschatology we know of.
Eschatologies of particular religions:
Ancient religions (no longer widely practised)
Modern day religions (still widely practised)
Science does not have an eschatology as such, but the study of cosmology does deal with theories about the possible origins and the ultimate fate of the Universe. The emerging concept of a multiverse, possibly infinite, appears to contradict the idea of a definitive end to existence itself, and the scientific study of time calls into question the very meaning of concepts like "beginning" and "end".