Jeanne Dark is a post-punk, shoegaze, industrial, and doom project from Zurich, Switzerland (listed under Hungary), that emerged in 2024 using raw analog technology and mystical sounds. Their debut singles including Guillotine and Der Apparat explore themes of mental anguish through atmospheric, genre-blending dark alternative music inspired by the historical French freedom fighter.

Jebes Ime is a Croatian heavy band from Dakovo that blends blues, crust, grindcore, hardcore, sludge, and stoner rock into an aggressive hybrid. Their album Dakovo je umiruca kurva (2012) was recorded at Studio Pecina, delivering four tracks of diverse, genre-crossing heaviness.

Jechane is a Polish metal band from Tuczno whose debut album War in Your Head (2016) delivers thrash, death, and progressive metal with heavy growl vocals and thrashy guitars. Recorded at Szafa Records Studio, the album features thirteen tracks exploring themes of mental conflict and psychological darkness.

Jenner is a heavy/thrash metal band from Belgrade, Serbia, formed in 2013 and delivering energetic, riff-driven metal. Their releases including Prove Them Wrong and To Live Is To Suffer channel classic thrash aggression through a tightly wound Serbian metal sound.

Jerk is a thrash metal band from Switzerland that delivers aggressive, high-energy metal with a raw and confrontational edge. Their stripped-down approach to thrash draws on the intensity of the genre's classic era while maintaining a distinctly Swiss underground identity.

Jester Beast is a thrashcore band from Turin, Italy, formed in 1983 and known for evolving from power/speed metal into crazily fast thrashcore blending Italian hardcore with Voivod-esque riffs. Their 1988 demo was significant enough for Nuclear Blast Records to feature three tracks on a compilation, and The Lost Tapes Of... Poetical Freakscream (2018) remastered that overlooked Italian thrash gem.

Jihad is a heavy metal band from Poland that delivers aggressive, confrontational compositions with dark thematic content. Their uncompromising approach to extreme metal channels raw intensity through punishing riffs and powerful performances.

Jim T is the solo project of Dimitar Todorov from Kavala, Greece, former guitarist and drummer of the black metal band Mold of Tree. His releases including Deadly Nature feature original metal instrumentals alongside covers of Septicflesh and Gojira, showcasing his versatility across extreme metal styles.

Jimmy Oldfield is a solo metal musician from the United Kingdom who has released five albums spanning groove, heavy, thrash, and stoner metal. His most recent release Immortal Form (2023) features vocalist Jeffery Yu alongside his own instrumental work, all self-produced with a Creative Commons approach to distribution.