Black Flag  is an American hardcore punk band formed in 1976 in Hermosa Beach, California by Greg Ginn, the band's guitarist, primary songwriter, and sole constant member. During Black Flag's 10-year existence, the band went through 16 distinct lineups involving 17 different musicians. Aside from Ginn, the longest-lasting members were bassist Chuck Dukowski (6 years), vocalist Henry Rollins (5 years), vocalist Keith Morris (3½ years), and drummer Roberto "Robo" Valverde (3½ years). The 1983–1985 lineup of Ginn, Rollins, bassist Kira Roessler, and drummer Bill Stevenson  recorded four albums and three EPs together in a sixteen-month period. After breaking up in 1986 and briefly reuniting in 2003, Black Flag announced another reunion in January 2013. Two versions of Black Flag are currently touring; the Ginn-fronted band known as Black Flag, and a group featuring founding vocalist Keith Morris and other previous members known simply as Flag.

Members

Current members (Black Flag)
 Greg Ginn – guitars, backing vocals (1976–1986, 2003, 2013–2014, 2019–present)
 Mike Vallely – lead vocals (2003, 2013–2014, 2019–present)
 Charles Wiley – drums (2022–present)
 Harley Duggan – bass (2022–present)

Current members (Flag)
 Keith Morris – vocals (1976–1979, 2013–present)
 Chuck Dukowski – bass (1977–1983, 2013–present)
 Dez Cadena – vocals (1980–1981, 2003, 2013–present), rhythm guitar (1981–1983, 2003, 2013–present)
 Bill Stevenson – drums (1983–1985, 2013–present)
 Stephen Egerton – lead guitar (2013–present)

Former members
 Raymond Pettibon – bass (1976)
 Bryan Migdol – drums (1977–1978)
 Kansas (Jim Dearmen) – bass (1977)
 Glenn "Spot" Lockett – bass (1977; died in 2023)
 Roberto "Robo" Valverde – drums (1978–1981, 2003)
 Ron Reyes – lead vocals (1979–1980, 2013)
 Henry Rollins – lead vocals (1981–1986)
 Emil Johnson – drums (1982)
 Chuck Biscuits – drums (1982)
 Kira Roessler – bass (1983–1985)
 Anthony Martinez – drums (1985–1986)
 C'el Revuelta – bass (1986, 2003; died in 2017)
 Gregory Moore – drums (2003, 2013–2014)
 Dave Klein – bass (2013)
 Isaias Gil – drums (2019–2022)
 Joe Noval – bass (2019–2022)

Member history
Ginn formed the band with singer Keith Morris in the summer of 1976. Ginn's younger brother Raymond—known later by his pseudonym Raymond Pettibon—played bass guitar with them in early rehearsals but soon bowed out of the group to focus on his college education. To fill out the rhythm section Morris recruited some of his friends, whom he described as "scruffy beach rat types who were more interested in getting laid and finding drugs than really playing". By early 1977 these included a bassist known only as "Kansas" and drummer Bryan Migdol, though both would frequently skip rehearsals. The band originally called themselves Panic. Ginn's friend Glenn Lockett, also known as Spot, played bass guitar with the group during rehearsals in early 1977. Würm bassist Gary McDaniel, who later adopted the pseudonym Chuck Dukowski, began sitting in with the band and soon became their permanent bassist. Spot became a recording engineer and record producer, recording the band's releases over the next eight years and working with many of the other bands on Ginn and Dukowski's independent record label SST. Panic changed their name to Black Flag in 1978, and released their debut EP Nervous Breakdown in January 1979.

Migdol left and was replaced by Robo, a Colombian national. Morris recorded basic tracks for Black Flag's second release, but left the band to form the Circle Jerks shortly before Black Flag was to embark on a summer 1979 West Coast tour. He was replaced by Ron Reyes, who also recorded tracks for the band's second release but quit mid-performance in May 1980. The band convinced him to return to finish recording the Jealous Again EP (1980), then replaced him with Dez Cadena in June 1980. Cadena sang on the "Louie Louie" single (1981) and both sang and played guitar on the Six Pack EP (1981), but his voice suffered from the strain of constant touring and he expressed a desire to move to guitar. When the band toured the East Coast of the United States in December 1980, they met Washington, D.C. native and State of Alert singer Henry Garfield, who stayed in touch with Dukowski. When they returned to the East Coast that spring, Garfield jumped on stage at a New York City show and sang a song with them. A few days later they asked him to audition in New York City and offered him the position of lead singer. After settling his affairs at home, Garfield met up with Black Flag in Detroit and sang at soundchecks and encores throughout the rest of the tour while Cadena continued to sing the main sets. On arriving in Los Angeles with the band, Garfield took the pseudonym Henry Rollins.

The five-piece Black Flag lineup of Ginn, Dukowski, Robo, Cadena and Rollins recorded the band's first full-length album, Damaged, in 1981. However, Robo encountered visa problems at the end of a December 1981 tour of the United Kingdom and could not legally return to the United States. Descendents drummer Bill Stevenson was brought in to finish the tour with a week of East Coast dates. For the first half of 1982, sixteen-year-old Emil Johnson drummed for Black Flag, playing on the title track of the TV Party EP, but quit in the middle of a U.S. tour after a fight with the band's roadie Mugger. He was replaced by Chuck Biscuits of D.O.A., but Biscuits lasted only several months as he would not agree to the band's demanding rehearsal schedule. With the Descendents on hiatus, Bill Stevenson joined Black Flag in early 1983 as their new drummer, and the band toured the United States and Europe. Cadena left Black Flag in April 1983 to form his own band, DC3, and was not replaced. Ginn also attempted to edge out Dukowski, desiring a new musical direction, and in the fall of 1983 Rollins took it upon himself to fire Dukowski from Black Flag in order to resolve the situation. Dukowski remained involved with Black Flag, acting as their manager and booking agent.

Throughout 1982 and 1983, the band had been in a legal dispute with Unicorn Records over the rights to Damaged that had prevented them from releasing material under the Black Flag name, though they had released the 1982 compilation album Everything Went Black, consisting of demos recorded during Morris, Reyes, and Cadena's stints as singer (Morris was credited as "Johnny 'Bob' Goldstein" and Reyes as "Chavo Pederast"). When Unicorn went bankrupt in late 1983, the band was free to release new material and recorded their second album, 1984's My War, with Ginn playing bass guitar under the pseudonym Dale Nixon. Shortly after the album's recording, Kira Roessler was added as the band's new bassist. The lineup of Ginn, Rollins, Stevenson, and Roessler was Black Flag's most prolific, releasing three more albums in 1984 (Family Man, Slip It In, and Live '84) along with two more albums (Loose Nut and In My Head) and an EP (The Process of Weeding Out) in 1985.

Stevenson was fired from Black Flag by Ginn in late April 1985 and returned to the Descendents. He was replaced by Anthony Martinez, who toured North America with the band and played on the live album Who's Got the 10½? (1986). Roessler was fired in September 1985 and replaced by C'el Revuelta, who performed on the band's final tour from January to June 1986. Ginn disbanded Black Flag that August.

In September 2003, Ginn organized three Black Flag reunion shows to benefit cat rescue organizations. The lineup for these performances was Ginn on lead guitar, C'el Revuelta on bass, Dez Cadena on rhythm guitar and co-lead vocals, and Robo on drums. Pro-skateboarder Mike Vallely sang for Black Flag and drummer Gregory Moore was on the drums for one of the sets of this show when the band played the entire My War album with a pre-recorded bass track by Ginn.

In January 2013, Ginn announced that he was reuniting Black Flag with Ron Reyes on vocals and Gregory Moore on drums and that the band would make a European and North American tour as well as release a new album. Black Flag has been confirmed to headline the Hevy Festival in the U.K., the Ruhrpott Rodeo Festival in Germany and the Muddy Roots Music Festival in Cookeville, Tennessee in 2013. In November of the same year, Reyes was fired on stage and replaced by Mike Vallely from Ginn's other band Good for You.

Also in January 2013, other former Black Flag members who are estranged from Greg