William Thomas Hader Jr. (born June 7, 1978) is an American actor, comedian, and filmmaker. He was a cast member on the NBC sketch comedy series Saturday Night Live from 2005 to 2013, for which he received four Primetime Emmy Award nominations and a Peabody Award. He became known for his impressions and especially for his work on the Weekend Update segments, where he played Stefon, a flamboyant New York City nightclub tour guide. Hader co-created the HBO dark comedy series Barry (2018–2023) with Alec Berg, in addition to playing the title role of Barry Berkman. He also served as producer, writer and director, for which his efforts garnered him eight Emmy Award nominations for the series. He won two, consecutively, for Outstanding Lead Actor in a Comedy Series. He is a star and producer of the IFC mockumentary comedy series Documentary Now! (2015–2022) along with Fred Armisen and Seth Meyers. He was Emmy-nominated for his guest role in Curb Your Enthusiasm in 2022. In film, he took supporting roles in Hot Rod (2007), Superbad (2007), Forgetting Sarah Marshall (2008), Adventureland (2009) and The BFG (2016), with leading roles in The Skeleton Twins (2014), Trainwreck (2015), and as an adult Richie Tozier in It Chapter Two (2019). His extensive voice acting work includes such as the Cloudy with a Chance of Meatballs film series (2009–present) and The Angry Birds Movie franchise (2016-present), Monsters University (2013), Inside Out (2015), Finding Dory, Sausage Party (both 2016), Toy Story 4 (2019), and Lightyear (2022), and the upcoming The Cat in the Hat (2026).