The Fantastic Four are Invisible Woman, the Human Torch, The Thing, and Mr. Fantastic. Unless The Thing leaves and then She-Hulk takes his place. Or if Wolverine, Ghost Rider, Spider-Man, and the Hulk happen to be around.
Or if there are more than four people on the team. Or if any of them happen to be dead or missing in another dimension.
Fantastic Four was the foundation of the Marvel Universe….