I know the traditional view is John the son of Zebedee, aka John the Apostle. But I've read diferente perspectives, even Mary Magdalene or even Judas! I've read about the Lazarus theory, it seeems compeling at first but there's something that makes me doubt it.
The Muratorian fragment says it was really a John who wrote a gospel, but they cal him a "disicple" while they cal others "apostles".
The authorship of the Gospels is a fascinating topic, even if you're not religious. But I remember being taught that the author John was not John the Apostle because it was written long after Jesus. Never heard the "Lazarus" theory.