Black was born in California, the son of two satellite engineers, Judith (née Cohen) and Thomas William Black; his mother worked on the Hubble Space Telescope. Jack Black's mother is Jewish and his father converted to Judaism; Black was thus raised Jewish. On The Tonight Show he said his surname may come from the Scottish occupational name Blacksmith. His parents divorced when he was 10. Jack Black had a Bull Mastiff and Rottweiler mix named Chico. Chico died of parvovirus soon after Jack's parents divorced. Black moved to Culver City with his father and frequently visited his mother's home until the end of his first year of college at UCLA when his father's family moved to France. As a child, Black appeared in an early Atari Pitfall! commercial, which was later shown during an appearance on Jimmy Kimmel Live and again on The Tonight Show with Jay Leno.
When he entered high school, his parents suggested that he should transfer to the Poseidon School, a private secondary school engineered specifically for students struggling in the traditional school system. Black eagerly accepted the proposition, afraid that he would only be bullied if he remained in public school.
He also attended the Crossroads School, where he excelled in drama. Black later attended UCLA but dropped out during his sophomore year to pursue a career in the entertainment business, at which point his father discontinued his financial support. Fellow UCLA veteran Tim Robbins later cast Black in Bob Roberts. He also had recurring roles on the HBO sketch comedy series Mr. Show.
Black's acting career began with primetime TV. He played roles on several shows such as: The Golden Palace (Taxi Driver), Life Goes On (skinhead), Northern Exposure (Kevin Wilkins, prom king), HBO's Mr. Show, and Picket Fences (Curtis Williams). In a Season 3 episode of The X-Files, titled "D.P.O.", Black played Bart 'Zero' Liquori, friend to Darren, a teen who could cause lightning strikes, played by Giovanni Ribisi. Black appeared in an un-aired pilot episode for a show directed by Ben Stiller called Heat Vision and Jack where he played an ex-astronaut pursued by actor Ron Silver. He was accompanied by his friend who had merged with a motorcycle, voiced by Owen Wilson.
Black later took on small roles in Airborne, Demolition Man, Waterworld, The Neverending Story III, The Cable Guy, Bob Roberts, Mars Attacks!, The Jackal, Bye Bye Love, Jesus' Son, Dead Man Walking, Saving Silverman, Enemy of the State, and I Still Know What You Did Last Summer. In High Fidelity, he was cast in the role of Barry, the pretentious co-worker to John Cusack's record store owner, which garnered him more exposure.
His career soon led to leading roles in films such as Shallow Hal, Orange County, School of Rock, Envy, Be Kind Rewind, King Kong, and Kung Fu Panda. Black starred in two films in 2006: Nacho Libre, in which he played a Mexican friar following his childhood dream of wrestling and pursuing true victory by fighting for the children of an orphanage, and Tenacious D in: The Pick of Destiny, a fictionalized account of the band's formation and their quest to obtain a "supranatural" guitar pick. Nacho Libre opened on June 16, 2006; Tenacious D in: The Pick of Destiny was released November 22, 2006.
He starred alongside Jude Law, Cameron Diaz, and Kate Winslet in The Holiday, in which he played Miles, the love interest of Winslet's character. In 2007 Black starred in Margot at the Wedding, opposite Jennifer Jason Leigh and Nicole Kidman, released November 16, 2007.
Black's comedic style combines many key elements from both sides of the traditional double act. Black typically begins a skit in which he presents an earnest introduction to a premise or subject that quickly reveals itself to be flawed or fundamentally ludicrous. Black then switches completely to a far-extreme caricature of human emotion.