Written by Marc Guggenheim with a special contribution from Stan Lee, the milestone comic features two tales from alternative Marvel Universes.
The title's solicitation reads: "In the first towering tale of a Marvel Universe that never was, see what would have happened had Norman Osborn's bloody siege of Asgard actually succeeded. Which heroes would have survived?
"Then, Stan 'The Man' Lee returns to take his Fantastic Four classic, 'The Coming of Galactus', to unthinkable heights that must be seen to be believed! The all-seeing Watcher brings together two generations of Marvel classics this December."
Dave Wilkins and Dale Eaglesham will handle interior artwork on the book. The former will also provide the cover illustration.
What If? #200 arrives in stores on December 29.