Leon Russell, a rock 'n roll legend known as the “Master of Space and Time,” died on Sunday at home in his sleep. He was 74. Russell was inducted into the Rock and Roll Hall of Fame in 2011. Russell was good friends with Elton John, who posted a message on Instagram on Sunday morning. “My darling Leon Russell passed away last night. He was a mentor, inspiration and so kind to me,” John wrote. “Thank God we caught up with each other and made ‘The Union.’ He got his reputation back and felt fulfilled. I loved him and always will.” John and Russell recorded “The Union” album together in 2010.