As word spread, many on Facebook changed their profile pictures to that of the legendary Velvet Underground frontman's face, and Twitter erupted with appreciations from all corners of the globe.
"The world has lost a fine songwriter and poet... I've lost my 'school-yard buddy'," tweeted John Cale, who co-founded what would become the Velvet Underground with Reed in 1964, when both men were in their early 20s.
Those who knew and loved the musician, sometimes from up close and sometimes just from afar, also weighed in.
Aerosmith's Steven Tyler Tweeted, "RIP TO A GREAT FRIEND A FELLOW MUSICIAN. FROM MAXES TO THE MASSES YOU MADE THE WORLD SING. I LOVE YOU LOU!"
"I met Lou Reed and told him he gave me tinnitus at a concert in 1989 that never went away and it was worth it. Dirty Blvd. Love to Lou," wrote Judd Apatow.
Iggy Pop simply wrote, "Devastating news," and linked to the Rolling Stone article about Reed's death.
In a series of tweets, Tom Petty & the Heartbreakers keyboardist Benmont Tench wrote, "All deaths are tragic... But a great artist's death affects more people, more directly. They've illuminated your life through their work. So you take it personally, like the loss of a close friend. Reed meant a hell of a lot to me."
Guitarist Tom Morello from Rage Against the Machine and Audioslave chimed in, "My intro to Lou Reed/Velvet Underground was Jane's Addiction cover of 'Rock n Roll'. He was a singular, unique talent. RIP Lou and thanks."
Mia Farrow kept her appreciation short and sweet, "Deepest Gratitude Lou Reed. Peace." She included a link to the lilting tune "Perfect Day" from Reed's 1972 album, "Transformer," which David Bowie co-produced.
Superstar chef Anthony Bourdain checked in with a quote from the Velvet Underground tune "Sweet Jane," which was originally released on the band's 1970 album "Loaded": "'heavenly wine and roses seem to whisper to me .when you smile.' RIP Lou Reed."
John Lennon's son Julian tweeted, "RIP Lou...A Real Original...x," which was similar to what could be found on Bowie's Twitter feed. Bowie's tweet simply said, "RIP LOU REED."
Even Miley Cyrus, who was born almost two decades after the Velvet Underground broke up, had something to say, "noooooooooo notttttttttt LOU REED," she tweeted, including an emoticon of a broken heart.
By mid-afternoon Sunday, perhaps the most shared Reed quote on social media was, appropriately, "Satellite's gone up to the skies."