Dan Cusick, an HIV-positive AIDS activist and advocate for those recovering from addiction, died Thursday, April 23, due to hepatitis C–related liver failure, according to the Bay Area Reporter. He was 50 years old.

A longtime activist, participating in the antinuclear movement in his 20s, Cusick moved to San Francisco in 1990 where he became heavily involved in AIDS activism. He joined ACT UP/Golden Gate—later renamed Survive AIDS—and was a volunteer with treatment advocacy group Project Inform, counseling people through the organization’s HIV treatment hotline. Under the tutelage of the late Jeff Getty and the late Martin Delaney, Survive AIDS and Project Inform played a critical role in making organ transplants accessible to people living with HIV.

Beginning in 2002, Cusick managed the Castro Country Club, which provided a clean and sober alternative to the Castro’s bar scene while offering support to those struggling with drug and alcohol addiction. He was also a member of San Francisco Mayor Gavin Newsom’s crystal methamphetamine task force.

“Dan was the ‘Angel of Castro Street,’” said fellow activist Matt Sharp. “He saved many, many people and made lives more bearable for the living because it was the right thing to do, not for himself. He’s one of those people it’s hard to imagine not being among the living and the fighting.”