Saint John the Evangelist (d. ca. 110; יוחנן "The LORD is merciful", Standard Hebrew Yoḥanan, Tiberian Hebrew Yôḥānān), or the Beloved Disciple, is traditionally the name used to refer to the author of the Gospel of John and the First Epistle of John. Traditionally he has been identified with John the Apostle. The identification with the author of the Second and Third Epistle of John and the author of the Book of Revelation is a long-held tradition (see John the Presbyter and John of Patmos).

The Gospel of John refers to an unnamed "Beloved Disciple" of Jesus who bore witness to the gospel's message. The editors of the Gospel, who record the Beloved Disciple's death, seem interested in the author's anonymity. Apparently this disciple of Jesus had not been well known, but had greatly outlived Peter.

The apostle John was a historical figure, one of the "pillars" of the Jerusalem church after Jesus' death. Many scholars believe that John was martyred along with his brother, as Jesus predicts in Mark (Mark 10:39, Acts 12:1-2). The tradition that John lived to old age in Ephesus and that he wrote this gospel date from the late second century. Modern scholars generally do not regard John to have authored any of the texts ascribed to him.