Lewis Niles Black (born August 30, 1948) is an American stand-up comedian and actor. His comedy routines often escalate into angry rants about history, politics, religion and cultural trends.

He hosted the Comedy Central series Lewis Black's Root of All Evil and makes regular appearances on The Daily Show delivering his "Back in Black" commentary segment, which he has been doing since The Daily Show was hosted by Craig Kilborn. He was voted 51st of the 100 greatest stand-up comedians of all time by Comedy Central in 2004 and was voted 5th in Comedy Central's Stand Up Showdown in 2008 and 11th in 2010. In 2015, he appeared as the voice of Anger in the Pixar film Inside Out, a role he reprises in the 2024 sequel.

Lewis Black is also a spokesman for the Aruba Tourism Authority, appearing in television ads that first aired in late 2009 and 2010. He has served as an "ambassador for voting rights" for the American Civil Liberties Union since 2013. Since 2022, he has also been on the board of directors of the Kurt Vonnegut Museum and Library. He had been an honorary member of the board for about 10 years before that.

When not on the road performing, Black resides in Manhattan but also maintains a residence in Chapel Hill, North Carolina.

Lewis Black was born on August 30, 1948, in Washington, D.C., the elder son of Jeannette Black (née Kaplan; 1918–2022), a teacher, and Samuel Black (1918–2019), an artist and mechanical engineer. He had a younger brother, Ronald, who died of cancer in 1997 at the age of 47.

He is Jewish and was raised in a middle-class Jewish family in the Burnt Mills neighborhood of Silver Spring, Maryland. His grandparents emigrated from Chornyi Ostriv in Ukraine and Białystok in Poland and his paternal grandfather was originally named Leib Blech, later changed to Louis Black. Black graduated from Springbrook High School in 1966.

Black recounts in his book Nothing's Sacred that he scored highly on the math section of his SAT exam and later applied to Yale, Princeton, Brown, Amherst, Williams and Georgetown. Every college he applied to except Georgetown rejected him, but by that point he had decided he did not want to go there, so he attended the University of Maryland, College Park for one year before transferring to the University of North Carolina at Chapel Hill. There, he studied playwriting and was a brother of Pi Lambda Phi International fraternity and a member of Student Congress. After graduating in 1970, Black moved to Colorado Springs with a group of performers based in Chapel Hill, purchased an old log cabin theater and attempted to establish a theater company. Calling themselves the Homestead Arts Theatre, the group performed regionally at parks, schools, and prisons, but were unable to open the theater due to code violations. He eventually returned to Washington where he worked at the Appalachian Regional Commission, wrote plays, and performed stand-up comedy at the Brickskeler in Dupont Circle.

He earned an MFA degree at the Yale School of Drama in 1977, and was married for ten months when he was 26 years old.