revelator (n.)

"one who makes known events, deeds, etc., " mid-15c., agent noun from obsolete verb revelate "reveal" (1510s), from Latin revelatus, past participle of revelare (see reveal). "Rare and objectionable" [Century Dictionary]. As a title in the Mormon church, by 1850. John the Revelator for the author of the Biblical book of Revelation is by 1650s.