28. A few more than I would have guessed.
I have probably seen a few of the typical hired gun players too, but not been aware of who they were at the time.
Daniel Adair - Nickelback, Melbourne, 2006
Morgan Agren - Devin Townsend, Copenhagen, 2019
John Blackwell - Drum clinic, Melbourne, 2005
Tommy Clufetos - Ozzy Osbourne, Bergen, around 2011
Vinnie Colaiuta - Sting, Bergen, around 2013
Tre Cool - Green Day, Oslo, around 2009
Mickey Curry - Bryan Adams at least twice, in Bergen around 2001 and Melbourne around 2004
Brann Dailor - Mastodon, Bergen, around 2013
Virgil Donati - Drum clinic and performance with solo band, Melbourne, 2005
The Drumbassadors - Ultimate Drummer's Weekend, Melbourne, 2005
Mario Duplantier - Gojira, Bergen, several times (at least three)
Dom Famularo - Ultimate Drummer's Weekend, Melbourne, 2005 or 2006
Benny Greb - Drum clinic, Bergen, around 2015
Dave Grohl - Foo Fighters, Bergen (twice) and Melbourne
Gavin Harrison - Porcupine Tree, Bergen and Oslo, around 2008-2012
Taylor Hawkins - Foo Fighters, Bergen (twice) and Melbourne
Wil Kennedy - Ultimate Drummer's Weekend, Melbourne, 2005 or 2006
Tommy Lee - Mötley Crüe, Bergen, 2009
Dave Lombardo - Slayer, Bergen, around 2012
Mike Mangini - Drum clinic, Melbourne, 2005, and with Dream Theater, Oslo, around 2012
Nicko McBrain - Iron Maiden, Bergen, around 2011
Simon Phillips - Toto, Tysnes, around 2011
Mike Portnoy - Dream Theater, Oslo, 2001, 2004 and 2007, Avenged Sevenfold, Oslo, around 2010, and John Petrucci, Melbourne, 2006
Johnny Rabb - Ultimate Drummer's Weekend, Melbourne, 2005
Christoph Schneider - Rammstein, Bergen, around 2015
Tico Torres - Bon Jovi, Bergen, around 2014
Charlie Watts - Rolling Stones, Oslo, 1998
Max Weinberg - Bruce Springsteen, Bergen, around 2012