Paul Edward Valentine Giamatti (ˌdʒiːəˈmɑːti ; born June 6, 1967) is an American actor. He first garnered attention for his breakout role in Private Parts (1997) as Kenny "Pig Vomit" Rushton, leading to supporting roles in Saving Private Ryan (1998), Man on the Moon (1999), Big Momma's House (2000), and Big Fat Liar (2002).
He won acclaim for his leading roles as Harvey Pekar in American Splendor (2003), Miles Raymond in Sideways (2004), Mike Flaherty in Win Win (2011), and Richard in Private Life (2018), while continuing to play supporting roles such as Joe Gould in Cinderella Man (2005), which earned him a nomination for the Academy Award for Best Supporting Actor, Chief Inspector Uhl in The Illusionist (2006), Karl Hertz in Shoot 'Em Up (2007), Nicholas "Nick" Claus in Fred Claus (2007), Tom Duffy in (2011), Theophilus Freeman in 12 Years a Slave (2013), Ralph in Saving Mr. Banks (2013), Eugene Landy in Love & Mercy (2014), Dr. Lawrence Hayes in San Andreas (2015) and Jerry Heller in Straight Outta Compton (2015).
He played the titular character in the HBO miniseries John Adams (2008), which earned him a Golden Globe Award, a Primetime Emmy Award and Screen Actors Guild Award. He stars as U.S. Attorney Chuck Rhoades Jr. in the Showtime television series Billions (2016–present).
Paul Edward Valentine Giamatti was born June 6, 1967, in New Haven, Connecticut, the youngest of three children. His father, Angelo Bartlett Giamatti, was a Yale University professor who later became president of the university and commissioner of Major League Baseball. His mother, Toni Marilyn Giamatti (née Smith), was a homemaker and English teacher who taught at Hopkins School and had also previously acted.
His paternal grandfather's family were Italian emigrants from Telese Terme; the family surname was originally spelled "Giammattei" (dʒammatˈtɛi) before immigrating to the United States. Giamatti's other ancestries are German, Dutch, English, French, Irish, and Scottish. His paternal grandmother had deep roots in New England, dating back to the colonial era.