In the June 29, 2006 issue of Rolling Stone magazine, FOO FIGHTERS frontman/ex-NIRVANA drummer Dave Grohl talks about the latest release from CELTIC FROST, "Monotheist", which he calls the "comeback of the year" as well as "the heaviest, gloomiest, darkest, scariest metal album you're gonna hear for a long time."
Says Grohl: "I might be playing acoustic shows this summer, but I'm a metal guy at heart. And I'll tell you the comeback of the year: Swiss metal warriors CELTIC FROST! Because they haven't made a record in so long, this is a band that you may not have heard of — but it's not often that a group can take a fifteen-year hiatus and come back with a masterpiece. It's called 'Monotheist', and I can't remember the last time I was so excited about a record coming out — I was at Tower Records at midnight! (I'm joking, I got it on fuckin' iTunes, bitch!) It's the heaviest, gloomiest, darkest, scariest metal album you're gonna hear for a long time."
CELTIC FROST frontman Tom G. Fischer was one of the featured guest vocalists on the self-titled album from Grohl's metal side-project PROBOT, which was released in February 2004. Fischer said of the collaboration back in 2002, "We (Erol Unala of CELTIC FROST/APOLLYON SUN and Tom) have completed a song called 'Big Sky' with Dave Grohl for the PROBOT project. Dave provided me with the opportunity to write the lyrics for the song and sing the lead vocals, and Erol added some guitar. The lyrics turned into some of the most personal I have ever written, and the song's mood reminds me a bit of [CELTIC FROST's] 'Mesmerized'."