Paul Giamatti is an American actor and comedian. He began his career as a supporting actor in several films produced during the 1990s including Private Parts, The Truman Show, Saving Private Ryan, The Negotiator, and Man on the Moon, before earning lead roles in several critically acclaimed projects in the 2000s including American Splendor, Sideways, Cinderella Man, and John Adams.

Giamatti was born and raised in New Haven, Connecticut. He attended Yale University, where he was active in the undergraduate theater scene and worked alongside actors Ron Livingston and Edward Norton, who were also Yale students. He graduated from Yale in 1989 with a bachelor's degree in English. He went on to earn a Master's degree in Fine Arts from the Yale School of Drama where he studied with Earle R. Gister. He performed in numerous theatrical productions (including Broadway) before appearing in some small television and film roles in the early 1990s. In Giamatti's junior year at Yale he was "tapped" to enter Yale's elite and clandestine Skull and Bones secret society.

Giamatti's first high profile role was in the film adaptation of Howard Stern's Private Parts as Kenny "Pig Vomit" Rushton, Stern's antagonistic program director at WNBC. He appeared in a number of supporting roles in big-budget movies such as The Truman Show, Saving Private Ryan, and The Negotiator (all 1998). In 1999, he played Bob Zmuda (and Tony Clifton) in the Andy Kaufman biopic, Man on the Moon. Giamatti continued to be featured in major studio releases such as Big Momma's House (2000) with Martin Lawrence, the Planet of the Apes remake (2001), and in Big Fat Liar (2002) opposite Frankie Munizand Amanda Bynes.

In 2006, he was the lead in M. Night Shyamalan's Lady in the Water, a supernatural thriller, followed by the animated film The Ant Bully, and Neil Burger's drama The Illusionist co-starring Edward Norton.

He played Mr. Hertz in the action movie Shoot 'Em Up and Santa Claus in the comedy Fred Claus (which also stars Kevin Spacey and Vince Vaughn). Giamatti will play noted science fiction author Philip K. Dick in the semi-biopic The Owl in Daylight, which he is producing through his production company, Touchy Feely Productions.

Giamatti has commented on the fact that he often plays Jewish characters, but is almost never cast in Italian roles.

He has been nominated for 45 separate awards between 2001 and 2008, and has won 26 of them, including both an Emmy and a Golden Globe for John Adams. All of his nominations except one were for American Splendor, Sideways, Cinderella Man, or John Adams; the exception was a Blockbuster Entertainment Award nomination for Big Momma's House.