Chicago XI is the ninth studio album by the American rock band Chicago. It was released on September 12, 1977, through Columbia Records. It was both the last to feature guitarist and vocalist Terry Kath prior to his death in a gun accident just over four months later, and the last to be produced by longtime associate of the band James William Guercio.

Chicago is an American rock band formed in Chicago in 1967. The group began calling themselves the Chicago Transit Authority in 1968, then shortened the name in 1969. Self-described as a "rock and roll band with horns," their songs often also combine elements of classical music, jazz, R&B, and pop music.