Former Holy Terror vocalist Keith Deen has passed away at the age of 56. The metal musician was recently diagnosed with cancer and, unfortunately, Deen lost his battle with the disease.

Deen lent his talents to the thrash/speed metal band Holy Terror's 1987 debut full-length, 'Terror and Submission' and 'Mind Wars' the year after. Shortly after Holy Terror released 'Mind Wars,' Deen left the band, leading to the act's eventual breakup.

Guitarist Kurt Cofelt (aka Kurt Kilfelt), who founded Holy Terror after leaving Agent Steel, re-formed Holy Terror in 2005, even releasing the album 'El Revengo' in 2006. However, Deen declined Cofelt's invite to rejoin the group at that time. After learning of Deen's passing, Cofelt stated, "With the loss of Keith Deen, a part of me is gone as well."

The webmaster of a Holy Terror fan site posted a memoriam that serves as a touching tribute to Deen:

At approximately 7:30 PM on December 15th, 2012 I was informed by my dear friend Chris Carlson from Chicago that Keith Deen of Holy Terror passed away. He had been battling cancer since September of 2012. Like any normal person, it blew through me like a heat wave. My plan was to go for a walk when I got home which was where I was heading when I got Chris' message about Keith. So, I got home and went for my walk. A permanent piece of real estate on my iTouch is dedicated to Holy Terror as one would expect. So, I queued up the "El Revengo" recordings and hit the pavement. The house I bought last year is in the neighborhood I grew up in and as I walked I started to remember a younger, plump, mullet headed version of myself riding my GT Performer up and down these same streets tossing papers on porches to the same soundtrack I was listening to right now. Sometimes it is good to relive the past, at least to a small degree. On that thought though, I am not a very big fan of nostalgia anymore. But, some things I just can't deny. Keith Deen fucking ruled. Keith Deen Roared.

Keith Deen Screeched.

Keith Deen Yelled.

Keith Deen Sang. If you listen to Both Terror and Submission & Mind Wars, you will agree that Keith Deen covered pretty much every style of vocal delivery imaginable in just those 2 albums. I often wonder what Holy Terror as a band would have done and created if they had stayed together. The past is the past though, and I know that the guys in the band would say the same thing. So with that I would like to speak directly to Keith..... Keith, Thank You for Roaring at me.

Thank You for Screeching at me.

Thank You for Yelling at me.

Thank You for Singing to me. Thank you for joining Holy Terror all those years ago and giving speed metal a fresh new voice.

Thank you for being the co-writer of "The Immoral Wasteland", my all time favorite song. Thank you Keith, for being who you were. We will meet again my friend, and when that time comes, I am going to buy you a drink and ask if you would be interested in singing in my band……

We'd like to offer our condolences to the family and friends of Keith Deen. To celebrate the life and musical contributions of Deen, check out 'The Immortal Wasteland' from the 'Mind Wars' album in the player below.