Jack Frost is a gothic doom metal band from Linz, Austria, active since 2000 and led by a collaboration with Michelle Darkness. Their discography spans eight albums from Gloom Rock Asylum (2000) through Lon Chaney (2025), crafting music described as simultaneously menacing and delightful across a range of dark sonic textures.

Jackal-Headed Guard of the Dead is a doom metal band from Edinburgh, Scotland, whose name and aesthetic draw on ancient Egyptian necromantic imagery. Their releases including Grimoire, Exaanum, and The Sky Has Been Riven channel deliberately ominous and extreme doom metal steeped in dark mysticism.

Jaern is a doom metal band from Gothenburg, Sweden, established in 2019 and featuring a four-piece lineup including guitarist/vocalist Marko Brostrom. Their self-titled debut EP (2020) delivers four tracks of fuzzy, heavy doom with psychedelic and sludge elements, with the track Miasma earning particular praise from the Swedish underground doom community.

Jagannah was an experimental comedy/psychedelic doom band from Modena, Italy, active from 2006 to 2011 and self-described as having come from space, played for space, and gone to space. Their album Aneha Hi How (2017) features nine tracks blending Melvins-influenced doom with surreal humor and absurdist performance.

Jagannatha is an instrumental doom and stoner rock trio from Grenoble, France, creating extended psychedelic compositions since their 2016 debut. Their three albums culminating in Trimurti (2022) have earned devoted fans with meditative, heavy psychedelic jams that blend crushing doom with spacey exploration.

Jaggu is a heavy sludge and stoner metal band from Oslo, Norway, with four albums from Revenantian (2019) through SLUGGU (2023) recorded at Red Line Studio. Their sound blends metal, sludge, and stoner rock with guest contributions from musicians like Babs Johnson of Shaving The Werewolf.

Jasenovac is a funeral doom metal project from Spain, started in the fall of 2019 and dedicated to the slowest and heaviest form of extreme metal. Their releases including Rotten in Dismal Isolation and Wounds of Bitter Failure channel crushing, glacial riffs and oppressive atmospheres that define the funeral doom genre.

Jastreb is an experimental rock band from Zagreb, Croatia, blending krautrock, occult themes, and heavy psychedelia. Their albums including Orient and Occident (2016) feature an international lineup including drummer Blake Fleming, creating expansive, exploratory compositions that draw comparisons to the krautrock tradition.

Jegulja is a rock and metal band from Ljubljana, Slovenia, featuring a baritone guitar-driven sound with multiple albums including Anguilla Guerrilla and Exit Sandman. The three-piece has been active since at least 2013, cycling through several drummers while maintaining their heavy, low-tuned approach to Slovenian underground rock.