Julia Garner: Julia Garner. Actress: The Assistant. Julia Garner is an American actress and model. She has appeared in the films Martha Marcy May Marlene (2011), The Perks of Being a Wallflower (2012), Sin City: A Dame to Kill For (2014), and played leading roles in Electrick Children (2012), We Are What We Are (2013) and Grandma (2015). She also plays Ruth Langmore in the Netflix original series Ozark (2017) and in...