From Twitter:

Brian Wilson (Beach Boys): Robin was 'part of the family'. I love the Bee Gees voices, they're some of my favorite singers. I am so sad.

Lenny Kravitz: Another legend passed. My deepest sympathy to the Gibb family. The Bee Gees are the soundtrack to an iconic era that shaped a world wide phenomenon and culture. Their rhythms, melodies,and production is one of a kind and instantly warms the heart. Respect Lenny

Liam Gallagher (Oasis): ROBIN GIBB LEGEND LG

Peter Frampton: So sorry to hear Robin Gibb has lost his battle with cancer. My heart goes out to the entire Gibb family at this very sad time. RIP

Elton John: Elton John dedicates 'Don't Let The Sun Go Down On Me' to Robin Gibb at a recent concert in Las Vegas

Duran Duran: Sorry to hear about the passing of Robin Gibb of the BeeGees. Our condolences to his friends and family:

Bryan Adams: Robin Gibb RIP. Very sad to hear about yet another great singer dying too young.

Justin Timberlake: We have lost a truly brilliant musician today. One of my idols. My heart goes out to the Gibb family in this time of sorrow...RIP Robin.

Ronan Keating: Just heard about Robin Gibb. I am devastated. Can't believe it. May he rest in peace. My thought and prayers are with his family. X

Diane Warren:  Bee Gees have written some of the best songs in pop music history. #RIP Robin

Nile Rodgers: "Got the wings of heaven on my shoes, I'm a dancing man and I just can't loose" ~Bee Gees~ Robin Gibb RIP

Mick Hucknall (Simply Red):  RIP Robin Gibb. A musical giant.

Gary Barlow (Take that): I'm so sad to hear Robin Gibb has passed away.Such a great loss.His music will out live us all.

Heart: Bless the Brothers Gibb. Their family blend inspired many harmonies in the back of vans full of traveling...

Richard Marx: Robin Gibb RIP. The Bee Gees were so important to pop music. Huge loss.

Bruno Mars: R.I.P Robin Gibb

Skin (skunk anansie): R.I.P. Robin Gibb, I LOVE the BeeGees music, amazing songwriters, great voices, beautiful stories.

The script: _ R.I.P. Robin Gibb. We met Robin+Barry in NY. Such a lovely guy. Prayers 2 his family. 2 many Legends being taken from us 2 early :(

The Doors:  We send our condolences to the family and fans of Robin Gibb of the Bee Gees, who passed away today.

Hanson: So sad to hear of the loss of The Bee Gee's, @RobinGibb, Another legend lost. Our hearts go out to Barry Gibb and Robin's entire family

Paula Abdul: The Bee Gees were & are music legends. my thoughts & prayers are w/ Robin Gibbs' family & friends. xoP

Kim Wilde: I toured with Robin Gibb in Germany.Always a true gentleman.He has left us an amazing legacy.

Chris de Burgh: So sorry to hear of the death of Robin Gibb, who was hugely influential in the writing and performing of modern popular music....

Jermaine Dupri: BEE GEES ~ LOVE YOU INSIDE OUT ~: RIP ROBIN GIBB,MY FAVORITE BEE GEES RECORD BY FAR, "LOVE YOU INSIDE OUT"

Boy George: So sad to hear about the loss of Robin Gibb, my prayers to his loved ones! R.I.P.

Peter Andre:I am so absolutely gutted about Robin Gibb passing away . One of the true musical legends whom I was honored to be friends with . RIP

BBC.CO.UK - Robin Gibb: Tributes to 'brilliant' Bee Gee:  www.bbc.co.uk/news/entertainment-arts-18142493

Access Hollywood: stars react to the death of Robin Gibb: www.accesshollywood.com/justin-timberlake-jimmy-fallon-and-more-stars-react-to-the-death-of-robin-gibb_article_65040