African-American improviser, composer, and bandleader, an important figure in free jazz in the late 20th century.

Threadgill studied at the American Conservatory of Music in Chicago and Governors State University, University Park, Ill. In the 1960s he played gospel music on a national tour, rock music in a U.S. Army entertainment troupe, and blues in a Chicago band.

He joined the cooperative Association for the Advancement of Creative Musicians (AACM). Threadgill, with Fred Hopkins (bass) and Steve McCall (drums), formed the trio Air in 1971 to play Scott Joplin rags and original works. The group became noted for its close ensemble interplay and for Threadgill's own large-sounding flutes and clarinets and rugged, sometimes violent alto, tenor, and baritone saxophones. He also recorded with Roscoe Mitchell, Muhal Richard Abrams, and others.

The works Threadgill wrote for his seven-member Sextett (or Sextet) in the 1980s, he frequently presented irony, blues, and abstraction. With this aggressive-sounding group he achieved rich sonorities of woodwinds, brasses, strings, and drums, in compositions with memorable themes and active melodic and rhythmic counterpoint. He expanded upon this interplay in the 1990s with his group Very Very Circus, a septet with unusual instrumentation, which included two tubas and two electric guitars.