Jonas Kjellgren (Born 4 July 1977) is a Swedish musician and producer, now residing in Grangärde, Sweden. He has played for bands such as Carnal Forge and Dellamorte as their lead vocalist and played guitar for Centinex, Scar Symmetry and bass for October Tide. As a producer, he has worked with bands such as Sonic Syndicate, Zonaria, Steel Attack, 21Lucifers Darzamat and The Absence. He owns and operates Black Lounge Studios which many Swedish metal bands use to record, mix and master their albums, although most of his recent work was done at The Abyss which is owned by Peter Tägtgren. Jonas is known for playing 7-string guitars. He was previously endorsed by Jackson, but now plays on a White 7-string Dean Razorback.

Has in October of 2011 replaced Gustaf Jorde on Bass guitar in Swedish industrial metal band Raubtier. This after a short tour as Gustaf's stand-in