He also worked with French band Gojira and thrash icons Slayer during his career at Rick Sales Entertainment Group.
Longtime music manager Nick John died on Saturday, following a battle with pancreatic cancer.
John had worked at Rick Sales Entertainment Group for more than 20 years, where he worked with Slayer, Mastodon and Gojira.
"Thank you for your guidance, your wisdom, your never ending hard work and dedication to Mastodon, always pushing and reaching turning over every stone to make sure we were always protected and always had every opportunity any us could dream ," wrote Mastodon on Facebook. "Thank you for making yourself available morning noon and night to handle every crisis or situation that ever came up. Thank you for being so passionate and believing in us with such enthusiasm that we considered you part the band. Thank you for your calm demeanor, your level head and your sharp sense humor. Thank you for showing all us how to work our phones and computers with incredible patience NJ solutions. Thank you for your smile and your infectious laugh but most all, thank you for your unconditional love and friendship, we love you very much and are going to miss you more than we know. We love you Nick John. RIP."
Gojira also shared a statement on Facebook, saying, "We lost an exceptional human being this morning. Our manager and dear friend Nick John. We carry him in our hearts. Our thoughts go to Colleen John, his wife and to all who loved him."
John began his career in the music business in the early 1990s as an intern at Rick Rubin's Def Jam Recordings. Working with Slayer, he earned executive producer credits for the band's God Hates Us All, War at the Warfield and Soundtrack to the Apocalypse albums, as well as the Still Reigning DVD.
He signed Mastodon in 2006, helping the band go on to five Grammy nominations and a best metal performance win this year for Sultan's Curse. In 2012, he started working with the French metal band Gojira, who landed two Grammy nominations in 2016.
Late last month, Mastodon canceled its tour with Dinosaur Jr. "due to a critical situation a member the Mastodon family," according to a statement released by the group. The tour had been scheduled to start last Saturday.
See some social media remembrances from Brann Dailor and Brent Hinds Mastodon, Gojira and others in the metal community below.