There will never be another Marilyn Monroe; that was the whole point of the phenomenon and why her image endures the way it does. But the closest thing we have today is obviously Margot Robbie.
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Like Monroe, Robbie’s screen persona is directed at the male gaze and titillating the gazers without giving away too much. And like Monroe, she does it so effortlessly that a lot of people assume it isn’t really acting.
It’s kind of sad that Robbie needed to do an imitation of a historical person for whom extensive video footage exists (which is not that hard for a skilled actor - ask any drag performer in Vegas) in order to get an Academy Award nomination. Her work in crafting a Monroe-like screen persona that’s still uniquely her own is much more impressive.
Monroe herself wasn’t nominated for an Academy Award either, despite the fact that history has basically concluded that she is the top movie star of all time, or close to it. It all looks rather silly in retrospect. Look at the Best Actress nominees for 1953: are any of them as impressive as Monroe in Gentlemen Prefer Blondes?