apocalyptist

[ uh-pok-uh-lip-tist ]
/ əˈpɒk əˌlɪp tɪst /

noun

a writer of apocalyptic literature.
a person who adheres to the teachings of apocalyptic literature concerning the signs and events preceding the end of the world.
a person who holds to any teachings that predict a catastrophic end to the world.

Origin of apocalyptist

First recorded in 1825–35; apocalypt(ic) + -ist