Katherine Marie Heigl (; born November 24, 1978) is an American actress, film producer, and former fashion model. She started her career as a child model with Wilhelmina Models before turning her attention to acting, making her film debut in That Night (1992) and later appearing in My Father the Hero (1994) as well as Under Siege 2: Dark Territory (1995). Heigl then landed the role of Isabel Evans on The WB television series Roswell (1999–2002), for which she received nominations for Saturn and Teen Choice Awards.

From 2005 to 2010, Heigl starred as Izzie Stevens on the ABC television medical drama Grey's Anatomy, a role which brought her significant recognition and accolades, including the Primetime Emmy Award for Outstanding Supporting Actress in a Drama Series in 2007. Her best known film appearances include roles in Knocked Up (2007), 27 Dresses (2008), The Ugly Truth (2009), Killers (2010), Life As We Know It (2010), New Year's Eve (2011), The Big Wedding (2013), and Unforgettable (2017). Heigl has also starred in several films that have seen limited releases, including Jackie & Ryan (2014), Home Sweet Hell (2015), and Jenny's Wedding (2015). She also portrayed the lead role on the short-lived NBC television series State of Affairs from 2014 to 2015, and has lent her voice to the animated film The Nut Job (2014) and its 2017 sequel.

Additionally, Heigl has established herself as a cover model, appearing in numerous publications including Maxim, Vanity Fair and Cosmopolitan. She is married to singer Josh Kelley, with whom she has one son and two adopted daughters.