Fans of Marvel Comics have gotten used to fresh new takes on their traditional superheroes in recent years. Thor became a woman, a black man took over as Captain America, and the current Ms. Marvel is a Muslim teenager from Jersey City. On Wednesday morning, news emerged that yet another marquee character was in for a big change.

This time it's Iron Man, and a black woman named Riri Williams will be replacing billionaire playboy Tony Stark in the suit. The character, who was introduced earlier this year, will be headlining...