Marielle Stiles Heller /ˈmɑːriɛl/ (born October 1, 1979) is an American writer, director, and actress. She is best known for writing and directing the comedy-drama film The Diary of a Teenage Girl (2015), and directing the biographical drama film Can You Ever Forgive Me? (2018). In 2019, she directed the Fred Rogers drama film A Beautiful Day in the Neighborhood.
Marielle Heller was born in Marin County, California, to Steve Heller, a chiropractor, and his wife Annie Stiles-Heller, an artist and art teacher. She grew up in nearby Alameda, along with her younger brother and sister, Nate and Emily. Her father is from a Jewish family in New York. Heller started off as an actor, calling acting her "first love." As a child, she was part of the Alameda Children's Musical Theater, where she participated in as many as four plays a year, including the roles of Rabbit in Winnie the Pooh, Templeton the rat in Charlotte’s Web, and Polly in The Magician's Nephew.