It's the fifth time in the last eight weeks that a Marvel Comics-based movie has topped the U.S. box office, coming on the heels of "Captain America: The Winter Soldier," which had a three-week run at No. 1 in April, and "The Amazing Spider-Man 2," which kicked off summer on top earlier this month. Neither the Marvel superheroes nor "Godzilla" have been able to crack the $100 million mark with their openings however, though all have topped $90 million.