Holding John the son of Zebedee to be the author of Revelation are the second century church fathers Justin Martyr and Irenaeus, along with third century fathers Clement of Alexandria, Tertullian of Carthage, Origen of Alexandria, and Hippolytus of Rome.
Ignatius (35-107), Papius, Iraneus and Origin (185-254) assigned John the son of Zebedee as the author of the Gospel of John.
However, Papius identifies a separate John as the writer of the letters of John and Revelation, so there is some variance in early tradition as to authorship of the Johannine letters.
Unlike the other gospels, John the apostle is never named in the Gospel of John, though his name seems to be deliberately self-obscured by calling himself "another disciple" or the "disciple that Jesus loved" (John , -16, -27, 20:2-4, 20:8, 21:7, , -24).
Still, there is reason to believe that the traditional understanding here is correct.