Sir Cliff Richard has led the tributes for Bee Gee Robin Gibb who has died aged 62 after a lengthy battle with cancer.
"We are a fraternity of people who sing pop and rock and Robin is another one of us who has gone too soon," he said.
Many musicians including Ringo Starr, Stevie Nicks and Bryan Adams have been paying their respects via Twitter.
Former UK Prime Minister Tony Blair, a friend of Gibb, said he would "miss him very much".
"Robin was not only an exceptional and extraordinary musician and songwriter, he was a highly intelligent, interested and committed human being," added Mr Blair.
British-born Gibb's musical career began when he formed the Bee Gees with his brothers Barry and Maurice in 1958.
The group are among the biggest-selling of all time with hits spanning five decades, notching up album sales of more than 200 million worldwide.
Speaking of their contribution to music, Sir Cliff Richard said: "The legacy will be what the Bee Gees did, which was stunningly good stuff, right on a par with The Beatles."
Meanwhile, broadcaster Paul Gambaccini described the singer as "one of the major figures in the history of British music".
He echoed Sir Cliff and said: "Everyone should be aware that the Bee Gees are second only to Lennon and McCartney as the most successful songwriting unit in British popular music."
Robin Gibb had "one of the best white soul voices ever", Gambaccini said, adding that the group's accomplishments had been "monumental".
"Not only have they written their own number one hits, but they wrote huge hit records for Barbra Streisand, Diana Ross, Dionne Warwick, Celine Dion, Destiny's Child... the list goes on and on."
Former BBC Radio 1 DJ Mike Read, who was a family friend, said: "Robin had the voice, the pathos, and he was a great writer.
"He had a gift for melody and a gift for lyrics and left a phenomenal legacy, a phenomenal catalogue."
Referring to the Bee Gees, he said: "They had every award, every gold disc, every platinum disc, the Grammys, the lot, and had been doing it so long but were still so good at it."
The singer Dionne Warwick, whose biggest hit Heartbreaker was written by the Gibb brothers, said of Robin: "He was wonderful. He was a jokester.
"He had an incredibly witty sense of humour and was fun to be around. All three of them were sensational gentlemen first, just fun loving guys."
She touched upon the family members' close bond: "I think what was most attractive to me was how grounded they were.
"I think a lot of it has to do with their sense of family and being together as a family. I know exactly what that means, because I come from a family of singers. That is very important, to be connected. They loved each other very strongly and showed it, and it was a joy."
Musicians have been taking to Twitter to pay their respects.
Canadian singer Bryan Adams wrote: "Robin Gibb RIP. Very sad to hear about yet another great singer dying too young."
Justin Timberlake described Gibb as "a truly brilliant musician", adding: "One of my idols. My heart goes out to the Gibb family in this time of sorrow."
Gibb had battled ill health for several years.
In 2010, he cancelled a series of shows after suffering severe stomach pains while performing in Belgium. He went on to have emergency surgery for a blocked intestine.
His twin brother and band partner Maurice died in 2003 aged 53 following complications from a twisted intestine.
Robin Gibb cancelled a series of shows in Brazil in April 2011, after again suffering from abdominal pains.
Later that year, he was found to have cancer of the colon after having surgery on his bowel for an unrelated condition.
He was later also diagnosed with cancer of the liver, and underwent chemotherapy and surgery.
Last month the singer fell into a coma after contracting pneumonia.
Four weeks ago, he regained consciousness and was said to have been making a positive recovery. But his death was announced at 23:30 BST (22:30 GMT) on Sunday.