Black Flag is an American punk rock band formed in 1976 in Hermosa Beach, California. Initially called Panic, the band was established by Greg Ginn, the guitarist, primary songwriter, and sole continuous member, and singer Keith Morris. They are widely considered to be one of the first hardcore punk bands, as well as one of the pioneers of post-hardcore.

The band held their first performance in December 1977 in Redondo Beach, California. To avoid confusion with another band called Panic, they changed their name to Black Flag in late 1978. They played their first show under this name on January 27, 1979, at the Moose Lodge Hall in Redondo Beach, California.