Ian "Lemmy" Kilmister, who was also a member and sometime vocalist of the band Hawkwind in the 1970s, found that he was suffering from "an extremely aggressive" form of cancer on December 26 -- the day after Christmas. He died at home with his family.
"We cannot begin to express our shock and sadness, there aren't words," a short statement on the band's official Facebook page
"We will say more in the coming days, but for now, please...play Motörhead loud, play Hawkwind loud, play Lemmy's music LOUD.
"Have a drink or few.
"Celebrate the LIFE this lovely, wonderful man celebrated so vibrantly himself."
Known for his hard-drinking, hard-living lifestyle as much as his distinctive, gravelly vocal style, Lemmy was the sole constant member of the seminal rock band, which formed in 1975 and spanned 40 years.
He is survived by bandmates Phil Campbell and Mikkey Dee.
The band was hugely influential in the 1970s British rock scene and continued to shape the way hard rock and heavy metal was both played and appreciated worldwide.
Tributes flooded in from fans and fellow rock stars.
Mötley Crüe bassist Nikki Sixx said on Twitter that he would miss the influential British rocker, and called him a "(pillar) of dignity."
Former Black Sabbath vocalist Ozzy Osbourne tweeted: "Lost one of my best friends, Lemmy, today. He will be sadly missed. He was a warrior and a legend. I will see you on the other side."
Others stressed the importance of Lemmy's influence. Rock critic and Rolling Stone contributor David Wild paid tribute, saying: "There are people who play rock & roll. And there are people who ARE rock & roll. #RIPLemmy."