Sonny Barger, a founding member and public face of the notorious Hells Angels Motorcycle Club, has died at the age of 83, according to a post on his Facebook page Thursday morning.

With their leather vests and the roar of their engines as they cruised in packs on the open road, for many years the Hells Angels were a symbol – a frightening one for some Americans – of counterculture living.

Barger was a founding member of the international motorcycle club's original group, based out of Oakland, California in 1957.

As sanctioned offshoots of the club were established around the United States, and controversies around the group's activities compounded, Barger acted as a de-facto spokesperson, defending their outlaw lifestyle.

Barger was present at a notorious 1969 Rolling Stones concert in California, for which the Hells Angels had been hired as security, using their bikes as a makeshift barrier in front of the stage.

The unruly gathering at the Altamont Speedway is remembered for the death of Meredith Hunter, who was beaten and stabbed to death by members of the Hells Angels after he brandished a handgun near the stage.

By that point, the biker gang had already entered popular culture as a rough-and-tumble fraternity, through films, such as the 1967 "Hells Angels on Wheels" starring Jack Nicholson, and an in-depth 1966 profile written by Hunter S. Thompson, who spent a year living with the group.

For various gun and weapons charges, as well as a 1988 conviction for conspiracy to kill rival gang members, Barger spent over a decade of his life in prison, according to The Washington Post.

Due to a bout with throat cancer, he had his vocal cords removed later in life and used an electronic device to speak.

Barger had a role in the modern-day TV series "Sons of Anarchy" about a fictional biker gang, playing a character called Lenny "The Pimp" Janowitz.

"If you are reading this message, you'll know that I'm gone," his Facebook account said Thursday morning, adding he died after a battle with cancer.

"Although I've had a public persona for decades, I've mostly enjoyed special time with my club brothers, my family, and close friends," Barger said in the post.