She-Hulk

From The Guardian:

Among the many rumours floating around Iron Man before Marvel studio's firstborn fired its way into box office history was the suggestion that Hilary Swank might be making some sort of cameo. The word was that Ms Swank - who certainly has the requisite muscularity to play a superhero - would make an appearance, setting up a potential future solo film as She-Hulk or Black Widow. It was even apparently confirmed by producer Avi Arad.

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