Over at the SBL’s Bible Odyssey website, James McGrath has a post introducing laypersons to John the Apostle, John the Elder, and John of Patmos. I agree with James that these were three distinct individuals; I find his additional suggestion that Revelation might have been pseudonymous ascribed to John the son of Zebedee unlikely since this seer “John” never claims to be an Apostle and the “twelve Apostles” seem to be figures of the past (Rev 21:14). James rightly points out that the Fourth Gospel is technically anonymous, though he notes that the Apostle John was traditionally identified as the beloved disciple while Lazarus is one of the more recent suggestions, and he repeats the thesis recently championed by Hengel and Bauckham that the Elder John may be the author of the Gospel and Epistles. Check out the post if you are interested.
James McGrath on Ancient Christians named John