John Lennon's widow Yoko Ono paid tribute to Harrison, who she said brought magic to the lives of those who knew him.
"George has given so much to us in his lifetime and continues to do so even after his passing, with his music, his wit and his wisdom," she told The Press Association.
"His life was magical and we all felt we had shared a little bit of it by knowing him.
"Thank-you George, it was grand knowing you."
"He died with one thought in mind -- love one another," friend Gavin De Becker told The Associated Press, adding that Harrison's wife, Olivia Harrison, and son Dhani, 24, were with him when he died.
His former band-mate Sir Paul McCartney told the Press Association: "I am devastated and very, very sad. We knew he'd been ill for a long time.
He was a lovely guy and a very brave man and had a wonderful sense of humour. He is really just my baby brother."
Rest in peace, George. We love you. =(