At the end of her July 22 Mayhem Ball performance in San Francisco, Gaga exposed an Ozzy Osbourne T-shirt underneath a black leather jacket, then played his 1980 debut solo single “Crazy Train” as she and her dancers walked a catwalk.

Jack White, Metallica, Rob Zombie, Elton John and more paid tribute to Ozzy Osbourne after the Black Sabbath frontman died at 76 on Tuesday morning. Osbourne had been recovering from several spinal surgeries as well as his ongoing battle with Parkinson's disease.

Gene Simmons paid tribute to the fellow rock icon. "Sad to report Ozzy has passed away. He was a giant. Admired and loved by millions of fans worldwide. Prayers and condolences go out to the Osborne family," the KISS rocker wrote, sharing a link to news of his death.