CJ's Ghost is a possible myth in GTA V. Players and myth hunters believe that the myth of CJ's ghost is a very possible myth in GTA V.
It has been confirmed that CJ will not be appearing in GTA V, because GTA San Andreas is not in the same story arc (universe) as GTA V. GTA V takes place in the HD Universe, while GTA San Andreas is in the 3D Universe. However, many easter eggs are found in GTA V that reference CJ.
During the mission Hood Safari, while the player approaches Grove Street, 3 men can be seen riding their bikes in the opposite direction. These three men bear a strong resemblence to Carl Johnson, Big Smoke, and Ryder from the first mission in GTA San Andreas. This has been proven to be an Easter Egg. Also, Grove Street members can be heard saying "What's good, CJ?" or "Hey CJ", whilst talking on the phone. While this is probably a different CJ, some still speculate him to be alive.
In the Broker Safehouse in GTA IV, there is some graffiti scribbled on a wall next to the staircase. The graffiti contains references to previous protagonists of the GTA Series, including Tommy, Claude, Victor, Toni, and Carl Johnson. Next to Carl's name are the letters RIP, suggesting that Carl Johnson may be dead. However, this graffiti is a chronological error, because these characters do not belong to the same story arc as GTA IV.