Picture source: ssje.
‘The Gospel [of John] contains a reference to a character “The Beloved Disciple” or “The one whom Jesus loved.” This person is traditionally associated with John, whom is traditionally believed to be writer of the Gospel.
The Beloved Disciple does not appear in the Gospel until Jesus at supper with his Apostles/Disciples (Apostle is never used for the Disciples in John’s Gospel and the only Apostle — or one who is sent out with authority is Christ himself). The term or person appears directly in the narrative about six times:
- It is this disciple who, while reclining beside Jesus at the Last Supper, asks Jesus, after being requested by Peter to do so, who it is that will betray him.[Jn 13:23-25]
- Later at the crucifixion, Jesus tells his mother, “Woman, here is your son”, and to the Beloved Disciple he says, “Here is your mother.”[Jn 19:26-27]
- When Mary Magdalene discovers the empty tomb, she runs to tell the Beloved Disciple and Peter. The two men rush to the empty tomb and the Beloved Disciple is the first to reach the empty tomb. However, Peter is the first to enter.[Jn 20:1-10]
- In John 21, the last chapter of the Gospel of John, the Beloved Disciple is one of seven fishermen involved in the miraculous catch of 153 fish.[Jn 21:1-25] 
- Also in the book’s final chapter, after Jesus hints to Peter how Peter will die, Peter sees the Beloved Disciple following them and asks, “What about him?” Jesus answers, “If I want him to remain until I come, what is that to you? You follow Me!”[John 21:20-23]
- Again in the gospel’s last chapter, it states that the very book itself is based on the written testimony of the disciple whom Jesus loved.’
Source: R. Joseph Owles, ‘Who is “The Beloved Disciple”? What if It Is You?’ (A Sheep among Wolves).