You can go back to the Church Fathers and to see a number of significant ones taught the imminent return of Christ before allegory in Biblical interpretation reared its head. However, you asked for one person who "taught or believed the pre-trib rapture before the 19th century."
Ephraem of Nisibis (306-373)His sermon, On the Last Times, the Antichrist and the End of the World,” (ca. 373) is preserved in four Latin manuscripts and is ascribed to St.Ephraem or to St. Isidore. If not written by Ephraem, it is written by one greatly influenced by him. “All the saints and elect of God are gathered together before the tribulation, which is to come, and are taken to the Lord, in order that they may not see at any time the confusion which overwhelms the world because of our sins.”
Alexander offers an insightful comment on these words when he says, “This author, however, mentions another measure taken by God in order to alleviate the period of tribulation for his saints and for the Elect.” "In this sermon, Pseudo-Ephraem develops an elaborate biblical eschatology, including a distinction between the rapture and the second coming of Christ. It describes the imminent rapture, followed by 3½ years of great tribulation under the rule of Antichrist, followed by the coming of Christ, the defeat of Antichrist, and the eternal state. His view includes a parenthesis between the fulfillment of Daniel’s sixty-nine weeks and his seventieth week in Daniel 9:24-27.46 Pseudo-Ephraem describes the rapture that precedes the tribulation as “imminent or overhanging.”
I have read the sermon and the last paragraphs in the Latin make it clear the speaker believed the rapture happens at the end of the world.
But, even allowing your reading, one person out of millions of believers over hundreds of years makes my point nicely.