What does the G stand for GCallen in NCIS?

Answer 1

It doen't stand for anything but his first name on the show. G was raised in foster homes and no one really knew his real first name. So he was called G for some reason. He had many different nicknames when he was groing up and he never stayed in a foster home for long. He moved around a lot from foster home to foster home. The longest he ever stayed in a foster home was 3 months. Where he met a girl that was younger then him. In a couple of episodes she apeares as an older girl but G doen't reconize her. She had come to warn him that he was going to be shot. But she never got to tell him that. Instead he ended up getting shot but he survived. Later he found out that the girl was his little sister when she is murdered.