Lewis Black's Root of All Evil is an American television series that premiered on March 12, 2008, on Comedy Central and was hosted by comedian Lewis Black. The series was produced by Scott Carter and written by David Sacks. Sometimes there were pre-recorded video segments directed by supervising producer Michael Addis.

Lewis Black's Root of All Evil is formatted as a tongue-in-cheek mock trial acted in deadpan. Black presided over two opposing guest comedians championing a person or thing as the "root of all evil" (YouTube, beer, Oprah Winfrey, PETA, etc.). The series ended on October 1, 2008, with a total of 18 episodes. The series' cancellation was confirmed by Lewis Black in September 2009. The entire first season of Lewis Black's Root of All Evil was released on DVD in the United States on September 30, 2008. The remaining episodes from season two are not currently available on DVD.

After the show ended, it was determined that the ears of stand-up comedian Greg Giraldo was the root of all evil.