Last Roman Emperor or Last World Emperor is a figure of medieval European legend, which developed as an aspect of eschatology in the Catholic Church. The legend predicts that in the end times, a last emperor would appear on earth to reestablish the Holy Roman Empire and assume his function as biblical katechon who stalls the coming of the Antichrist. The legend first appears in the 7th-century apocalyptic text known as the Apocalypse of Pseudo-Methodius, and developed over the centuries, becoming particularly prominent in the 15th century. The notion of Great Catholic Monarch is related to it, as is the notion of the Angelic Pope.
The biblical foundations for the concept of the Great Monarch can be found in the Old Testament and in the New Testament. References in the Old Testament can be found in Isaiah, Jeremiah, Daniel and Zechariah. It is also found in the New Testament. Catholic teaching refers to the 25th chapter of Matthew's Gospel in which Christ says that no one knows the hour or the day, except the Father in Heaven. The Church furthermore teaches that Christ indicated the approximation of these events in the New Testament, when he spoke of signs which would indicate that the end of days was near. Some of these signs include natural disasters, civil problems, and other catastrophes. Of the precise time, however, it is unknown.
The legend is based on the Apocalypse of Pseudo-Methodius. It was developed in the writings of Adso of Montier-en-Der, and was particularly current around the end of the fifteenth century.Christopher Columbus refers to it in his Book of Prophecies.