Ozzy Osbourne passed away at 76, just weeks after his final Black Sabbath concert. Learn more about the health complications that led to his death and the official cause here.

Kelly Osbourne is mourning the death of her dad and rock legend Ozzy. On Thursday, the musician and daughter of the Black Sabbath frontman returned to social media for the first time, using the opening line to “Changes.” “I feel unhappy,” she wrote. “I am so sad. I lost the best friend I ever had.”