Black was born in Santa Monica, California, the son of two satellite engineers, Judith (née Cohen), who worked on the Hubble Space Telescope, and Thomas William Black. His mother is Jewish and his father converted to Judaism (Black attended Hebrew school). On The Tonight Show, he said his surname may have come from the occupational name Blacksmith. Black's parents divorced when he was 10; Black moved to Culver City with his father and frequently visited his mother’s home. As a child, Black appeared in a commercial for the Activision game Pitfall! in 1982, which was later shown during an appearance on Jimmy Kimmel Live and again on The Tonight Show with Conan O' Brien. When Black entered high school, his parents enrolled him at the Poseidon School, a private secondary school engineered specifically for students struggling in the traditional school system. Black also attended the Crossroads School, where he excelled in drama. He later attended UCLA but dropped out during his sophomore year to pursue a career in entertainment, at which point his father discontinued his financial support. Fellow UCLA alumnus Tim Robbins later cast Black in Bob Roberts. He also had recurring roles on the HBO sketch comedy series Mr. Show.