Gregory Regis Ginn (born June 8, 1954) is an American guitarist, songwriter, and singer.

He is best known for being the leader of and primary songwriter for the hardcore punk band Black Flag, which he founded and led from 1976 to 1986, and again in 2003. The band announced another reunion on January 25, 2013. He was born in Tucson, Arizona.

Since breaking up Black Flag, Ginn has recorded a few solo albums, and has performed with the bands HOR, Fastgato, October Faction, Gone, Killer Tweeker Bees, Confront James, EL BAD, Mojack, The Texas Corrugators, Jambang, Mexican Lions, and he also played bass with Tom Troccoli's Dog. He also owns the Texas-based independent record label, SST, originally begun as an electronics company called Solid State Transmitters when he was a teenager and amateur radio operator (in Hermosa Beach, California).

Ginn was 99th on Rolling Stone's list of "The 100 Greatest Guitarists of All Time". Ginn is the older brother of artist Raymond Ginn who goes under the pseudonym of Raymond Pettibon. Pettibon had contributed a large amount of visual imagery into Black Flag's works, including designing the band's iconic logo.