John the Apostle (Aramaic Yoħanna, Koine Greek Ἰωάννης) (c. AD 6 – c. 100) was one of the Twelve Apostles of Jesus. He was the son of Zebedee and Salome and brother of James, son of Zebedee, another of the Twelve Apostles. Christian tradition holds that he outlived the remaining apostles—all of whom suffered martyrdom (except Judas Iscariot)—and ultimately died of natural causes "in great old age in Ephesus" at the beginning of the second century. The Church Fathers consider him the same person as John the Evangelist, John of Patmos, and the Beloved Disciple.

The Church Fathers generally identify him as the author of five books in the New Testament: the Gospel of John, three Epistles of John, and the Book of Revelation. The Gospel according to John differs considerably from the synoptic gospels, likely written decades earlier than John's Gospel. The bishops of Asia Minor supposedly requested him to write his gospel to deal with the heresy of the Ebionites, who asserted that Christ did not exist before Mary. John probably knew and undoubtedly approved of the Gospels of Matthew, Mark, and Luke, but these gospels spoke of Jesus primarily in the year following the imprisonment and death of John the Baptist). Around 600, however, Sophronius of Jerusalem noted that "two epistles bearing his name ... are considered by some to be the work of a certain John the Elder" and, while stating that Revelation was written by John on Patmos, it was “later translated by Justin Martyr and Irenaeus”, presumably in an attempt to reconcile tradition with the obvious differences in Greek style. On the other hand, many authors in those days employed secretaries often called scribes whose personal styles influenced the final documents. John perhaps employed different scribes for his several works who dictated his words as he was influenced by the Holy Spirit through his meditation, visions, and dreams.