Slap-bass pioneer Louis Johnson of the Brothers Johnson passed away last Thursday (5/21). He was just 60 years old. The cause of deathe has yet to be revealed.

Between 1976-81, the sibling duo scored three #1 R&B hits: 1976's "I'll Be Good to You," a memorable 1977 cover of Shuggie Otis' "Strawberry Letter 23," and 1980's "Stomp!" Johnson doubled as a session pro, playing on Michael Jackson's Off the Wall, Thriller and Dangerous, among numerous sessions for producer Quincy Jones.

"Louis 'Thunder Thumbs' Johnson was one of the greatest bass players to ever pick up the instrument," Q told Rolling Stone. "As a member of the Brothers Johnson, we shared decades of magical times working together in the studio and touring the world. From my albums Body Heat and Mellow Madness, to their platinum albums Look Out for #1, Right on Time, Blam and Light Up the Night, which I produced, to Michael's solo debut Off the Wall, I considered Louis a core member of my production team. He was a dear and beloved friend and brother, and I will miss his presence and joy of life every day."

Ed Eckstein, who worked with the Brothers Johnson at A&M, posted this tribute on Facebook: “So sad to learn of the passing of my friend Louis Johnson, a once-in-a-generation musician (if we're so blessed) and a sweet, complex, hilarious guy. He was known to his family as ‘Boot’ and to the world as ‘Thunder Thumbs’—a name I gave him when we first met as roommates in a Denver hotel on the road with Quincy Jones. Along with his brother George, we traversed the world together while they made a joyful noise for millions of Brothers Johnson fans. My heart cries infinite tears to the family, particularly George and their eldest brother Joseph (Tommy); Louis' kids, Kodi, Kenji and Keiko; his grandchildren; his first wife Valerie Riffe, the mother of his kids; and all of those who were touched by his musical genius and personality. Love you Boot, rest in peace, you were loved and will be missed.”

RIP Louis Johnson. Now playing: all of these.

A photo posted by @desavia on May 22, 2015 at 4:05pm PDT

Instagram photo by Tom DeSavia