Original Beastie Boys' member and guitarist John Berry has died aged 52, according to reports.
Berry's father, John Berry III, confirmed the news to American music magazine Rolling Stone, and said his son had been suffering from frontal lobe dementia.
The musician, who is cited as the person who came up with the name for the band, died at a hospice in Danvers, Massachusetts.
The American rap rock band's many hits include (You Gotta) Fight for Your Right (To Party!), which was from their 1986 debut studio album, Licensed to Ill.
Berry was one of the founding members of the first incarnation of the band, called The Young Aborigines, formed in 1978.
Two years later the band changed its name to the Beastie Boys.
Vocalist Michael Diamond and Berry went to school together in New York, leading to a lifelong friendship rooted in music.
The pair were joined in the band by Adam Yauch and Kate Schellenbach.
The band's first EP, Polly Wog Stew, was released in 1982 and Berry left the band shortly after its release.
Schellenbach exited a year later and the new line-up came into being with Yauch and Diamond joined by Adam Horovitz on vocals and guitar.
Yauch died in 2012 following a battle with cancer, at the age of 47.
Fans paid tribute to Berry on Twitter, crediting their contribution to the music world, with one writing: "RIP to John Berry of the Beastie Boys. Those dudes started something bigger than music. Rap, rock and musicianship all in one. A new genre."
Schellenbach went on to become the drummer for rock band Luscious Jackson.
A message on the Luscious Jackson Facebook page said the band was "heartbroken hearing the news" of Berry's death.
It said: "He was a good friend and rabble rouser and if it wasn't for him, there'd be no Beasties, no Luscious Jackson, no Grand Royal and god knows what else. John brought us all together in his crazy wooden house on the UWS ... Rest In Piece friend ..."