Director Tim Story spoke about the decision to portray Galactus as a cloud in Fantastic Four: Rise of the Silver Surfer in the DVD's commentary.  "We decided early on that we would not bring him to life completely as you might think of him in the comics - being a man with the suit and the helmet and everything else," explained Story.

"One of the main reasons is because we always knew that there was going to be a Silver Surfer one, or they were going to make a spin-off of the Silver Surfer.  If I gave up everything in this movie, then that movie wouldn't have much to go on.  Knowing that I wasn't going to do it that early, I wanted to keep it fairly open to interpretation by the director who would do [the Silver Surfer movie].  So the idea of the cloud and everything made pretty good sense to us."

Story is currently working on an adaptation of The Losers for Warner Bros.  Fantastic Four: Rise of the Silver Surfer comes out on DVD Tuesday, October 2nd.