When the Pulitzer Prize–winning playwright Suzan-Lori Parks is at a creative impasse, she deploys her secret weapon: Mandy Hackett. “Her keen insights help me with my re-writes,” says Parks. The actor and writer John Leguizamo describes Hackett as a great storyteller and script doctor. The pop-music superstar Alicia Keys calls her “so special.”

The army of fans that Hackett, 53, has acquired over the years will come in handy as she prepares to leave her post as the No. 3 at the Public Theater, the vaunted New York nonprofit, and hang out her shingle as an independent producer.