Karl Groom

Iniziata l'attività come musicista nel 1988, nel 1990 è fondatore della band Threshold, nonché unico membro presente sin dall'inizio insieme a Richard West, e fu lui, nel 1991, a scegliere come etichetta per la band la Nuclear Blast.

Groom ha anche suonato la chitarra in Mercy Train, Shadowland e Strangers on a Train, tutti durante la metà degli anni 1990. Nel 2017, ha suonato tutte le chitarre acustiche nell'album Quiet Storms dei Galahad, da egli stesso coprodotto.^[3]

• 1993 - Skeleton in a Cupboard
• 1995 - The Greatest Show on the Earth

• 1992 – Wounded Land
• 1994 – Psychedelicatessen
• 1997 – Extinct Instinct
• 1998 – Clone
• 2001 – Hypothetical
• 2002 – Critical Mass
• 2004 – Subsurface
• 2007 – Dead Reckoning
• 2012 – March of Progress
• 2014 – For the Journey
• 2017 – Legends of the Shires
• 2022 – Dividing Lines

• Strangers on a Train - The Key Part I: The Prophecy (1990) p/e/m
• Threshold – Wounded Land (1993) p/e/m
• Pendragon – The Window of Life (1993) e
• Strangers on a Train - The Key Part II: The Labyrinth (1993) p/e/m
• Ulysses - Neronia (1993) p/e/m
• Threshold – Psychedelicatessen (1994) p/e/m
• Pendragon – Utrecht... The Final Frontier (1995) p/e/m
• Pendragon – 'The Masquerade Overture (1996) p/e/m
• Threshold – Extinct Instinct (1997) p/e/m
• Pendragon – Utrecht... The Final Frontier (1995) p/e/m
• Pendragon – Live In Kraków 1996 (1997)
• Threshold – Clone (1998) p/e/m
• DragonForce - Valley of the Damned (2003) p/e/m
• Threshold – Decadent (1999) p/e/m
• Threshold – Hypothetical (2001) p/e/m
• Pendragon – Not of This World (2001) p/e/m
• Threshold – Critical Mass (2002) p/e/m
• Threshold – Concert in Paris (2002) p/e/m
• Threshold – Wireless: Acoustic Sessions (2003) p/e/m
• Threshold – Subsurface (2004) p/e/m
• DragonForce - Sonic Firestorm (2004) p/e/m
• Threshold – Replica (2004) p/e/m
• Threshold – Critical Energy (2004) p/e/m
• Pendragon – Believe (2005) p/e/m
• DragonForce - Inhuman Rampage (2006) p/e/m
• Threshold – Surface to Stage (2006) p/e/m
• Edenbridge – The Grand Design (2006) e/m/g
• Threshold – Dead Reckoning (2007) p/e/m
• Threshold – The Ravages of Time (2007) p/e/m
• Edenbridge – MyEarthDream (2008) e/m/g
• Trigger the Bloodshed - Purgation (2008) m
• DragonForce -Ultra Beatdown (2008) p/e/m
• Pendragon – Pure (2008) p/e/m
• Clive Nolan – She (2008) e/m
• Trigger the Bloodshed - The Great Depression (2009) m
• Threshold – Paradox: The Singles Collection (2009) p/e/m
• Pendragon – Concerto Maximo (2009) p/e/m
• Edenbridge – Solitaire (2010) e/m
• Yes – In the Present - Live from Lyon (2011) e/m
• Pendragon – Passion (2011)
• DragonForce - The Power Within (2012) p/e/m
• Clive Nolan – Alchemy (2012) e/m
• Threshold – March of Progress (2012) p/e/m
• Edenbridge – The Bonding (2013) e/m
• Clive Nolan – Alchemy DVD Live (2013) e/m
• NightMare World - In The Fullness Of Time (2015) p/e/m
• Threshold - Legends of The Shires (2017) p/e/m