"Unholy" is a song by the American hard rock band Kiss, written by Gene Simmons and Vinnie Vincent. Featured on their 1992 album Revenge, the song is one of the three Vincent co-writes to appear on the album despite the fact that he had been fired from the band 8 years earlier. The release of "Unholy" signaled the return to a heavier sound for Kiss and was their first single to feature a lead vocal by bassist Gene Simmons since "I Love It Loud" in 1982 (a song also co-written by Vincent). The song was played live during the Revenge Tour and was included on the 1993 live album Alive III, but did not return to the live Kiss set list until 2004's Rock the Nation Tour.

"Unholy" was co-written by Gene Simmons and Vinnie Vincent, although Vincent was fired in 1984. Simmons stated in his book Kiss and Make-Up:
"Vinnie Vincent came up to me and apologized for causing the band all the grief while he was a member. He wanted to patch things up and wondered if I would consider writing some songs with him.
Sure, I said. I wanted to let bygones be bygones. I called Paul and told him that Vinnie had apparently changed. Paul wrote songs with him as well. But before the album was released, Vinnie was up to his old tricks again. He reneged on a signed deal we had made and decided that he wanted to renegotiate. He eventually sued us and lost. As far as I was concerned, he was persona non grata forever."

Two other songs which appear on the album, "I Just Wanna" and "Heart of Chrome", were also co-written by Vincent. The song is, according to Simmons, based on a Wicked Lester song "Keep Me Waiting" which appears on the album The Original Wicked Lester Sessions. Vincent suggested a number of changes, mostly lyrical changes which as Simmons said, made the song even better.

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