The Chicago Octet/Tentet is a live album by saxophonist Peter Brötzmann on which he is joined by two large ensembles known as the Chicago Octet and Tentet. Six tracks were recorded live at The Empty Bottle in Chicago on January 29, 1997, and September 17, 1997, while the remaining six tracks were recorded at AirWave Studio in Chicago on September 16, 1997. The album was released in 1998 as a limited-edition three-CD set by the Okka Disk label, and, in addition to Brötzmann, features saxophonists Mats Gustafsson, Joe McPhee, Ken Vandermark, and Mars Williams, trombonist Jeb Bishop, cellist Fred Lonberg-Holm, double bassist Kent Kessler, and drummers Hamid Drake and Michael Zerang.

Peter Brötzmann was a German jazz saxophonist and clarinetist regarded as a central and pioneering figure in European free jazz. Throughout his career, he released over fifty albums as a bandleader. Amongst his many collaborators were key figures in free jazz, including Derek Bailey, Anthony Braxton and Cecil Taylor, as well as experimental musicians such as Keiji Haino and Charles Hayward. His 1968 Machine Gun became "one of the landmark albums of 20th-century free jazz".