Photos of Katherine Heigl naked. Katherine Heigl is an American actress, film producer and former fashion model. We know her as Izzie Stevens in Grey’s Anatomy. She has also starred in films, such as Under Siege 2: Dark Territory, The Nut Job, Knocked Up, 27 Dresses, The Ugly Truth, Killers, Life As We Know It and New Year’s Eve. Age: 37 (November 24, 1978).