John Joseph McGowan (born October 3, 1962) is an American musician and author, most famous for his work as the lead singer of the hardcore band Cro-Mags. He is currently the vocalist of Bloodclot and was previously the vocalist of Both Worlds in the 1990s. He has been described by Blabbermouth.net as a "pioneer of the punk rock and New York hardcore genres."

John Joseph McGowan was born on October 3, 1962. His father was a well known boxer who was very violent towards his mother. Joseph once stated "The last memory I have of him was that he broke down the door one night to my mom’s house and beat her all over the apartment, and she ended up in the hospital. Broke her jaw, everything. That’s when they took us away and put us in the orphanages, and then they put us in foster care." McGowan and his two brothers were separated in foster care. He spent 5-7 years in the foster care system where he was beaten and starved.

By the age of 14 McGowan ran away from the foster home and began living on the streets of New York City. He also took to drugs such as heroin and began doing petty crimes, eventually getting shot in Forest Park. After serving time for a drug conviction McGowan joined the U.S. Navy in 1980. He would graduate with honors and became a physical training petty officer. His service would only last a year as he went AWOL after a physical altercation.

Before, during, and after his time in the Cro-Mags, McGowan served as a roadie for Bad Brains, and portrayed a mentally handicapped Santa Claus in a wheelchair pretending to beg for donations. McGowan orginally wanted to be a drummer, however Bad Brains lead singer H.R. told McGowan he had too much energy and should instead be a vocalist. So in 1981 McGowan and the rest of the Bad Brains roadies formed a band called Bloodclot and opened for them on their 1981 Summer tour.

McGowan then joined the New York City hardcore punk band Cro-Mags in 1981 as the lead singer and then again from 1984 until 1987, taking over on vocals from Eric Casanova. And rejoined in 1991 - He sang on a demo and wrote lyrics on the band's first, third, and fourth albums (The Age of Quarrel, Alpha Omega, and Near Death Experience). He also sings lead on the Before the Quarrel CD, essentially a reissue of the demo. The group disbanded in 2002, however McGowan and original drummer Mackie Jayson began playing shows under the Cro-Mags name again in 2009. With other notable NYC hardcore musicians such as Craig Setari from Sick of It All on bass and A.J. Novello from Leeway on guitar.

In 2018, original bass player Harley Flanagan filed a federal trademark infringement suit against McGowan and Jayson in the Southern District of New York. In April 2019, Flanagan announced a settlement wherein he would own exclusive rights to the name Cro-Mags; simultaneously, Joseph announced his recognition of the settlement, and that he and his band would perform as the Cro-Mags JM, having been granted a limited license to use the name in this manner, beginning in August 2019. Infringement by Joseph in 2022 resulted in a permanent injunction granted by the Federal District Court of the Southern District of New York. The rights to the Cro-Mags name now belong exclusively to Flanagan.

In 2024, McGowan revealed he would never take part in a Cro-Mags reunion with the classic lineup.

McGowan is also the lead singer of the hardcore band Bloodclot which can trace it’s origins back to 1981, when the idea was hatched during a Cro-Mags tour with Bad Brains. In 2008, Joesph transformed the group from a live act to a studio one, recording their debut Burn Babylon Burn! and releasing it via an independent label. In 2016, McGowan recruited an entirely new lineup consisting of Todd Youth, Nick Oliveri and Joey Castillo. The group signed with Metal Blade Records, to release their second studio album Up In Arms in 2017, and embarked on a worldwide tour. In 2022, McGowan once again recruited a whole new lineup featuring guitarist Tom Capone, bassist Craig Setari and drummer Darren Morgenthaler to release their third album Souls.