Member of the sketch comedy group Animals from the Future.
Attended Cascia Hall Prep School in Tulsa, Oklahoma.
His ex-wife, Maggie Carey, is a filmmaker who has won awards for both documentaries and narrative films.
Father manages an air freight company. Mother is a dance teacher.
His Saturday Night Live (1975) audition was him performing impressions of Al Pacino, James Mason, Tony Blair, and Peter Falk as Vinnie Vedecci, his Italian talk-show host character.
Monty Python, This Is Spinal Tap (1984), and early Woody Allen and Mel Brooks movies are his biggest comedic influences [Empire Online April 2008].
Part of Judd Apatow's stock company of actors. He has appeared in five of his films.
Has been in six films that have grossed over 100 million dollars (Knocked Up (2007), Superbad (2007), Tropic Thunder (2008), Night at the Museum: Battle of the Smithsonian (2009), Ice Age: Dawn of the Dinosaurs (2009) and Cloudy with a Chance of Meatballs (2009).
Is a producer on the 13th season of South Park (1997).
In an interview with Conan O'Brien, Star Wars: Episode IV - A New Hope (1977)-fan Bill stated that he knew the first time he saw his then-girlfriend's apartment, she would be his wife: she had "Star Wars" curtains in her living room.
Is allergic to peanuts.
Hader and his ex-wife (Maggie Carey) welcomed their first child, daughter Hannah Kathryn, on October 6, 2009. Their second daughter, Harper, was born on July 28, 2012 and third daughter, Hayley Clementine, on November 15, 2014.
In May 2013, he announced he would leave Saturday Night Live (1975) on May 18, 2013, at the end of the 2013 season. He further announced his plans to move to Los Angeles, so both he and his filmmaker wife (Maggie Carey, now ex-wife, as of 2018) could pursue more opportunities there.