Ironrat is a groove/stoner metal band from Bradford, United Kingdom, active since 2014 and delivering fuzz-laden, groove-heavy riffs through a haze of overdriven amplification. The project channels the riff-worshipping spirit of the genre.

Irreversible Mechanism is a Minsk-based progressive/technical metal project featuring Vladislav Nekrash on guitar and bass, Andrew Parmon on guitar, and Dan Presland on drums. Originally rooted in progressive death metal before incorporating stoner rock elements, the band is known for highly technical, instrumental-leaning compositions produced, mixed, and mastered entirely by Nekrash.

Isaak is a stoner metal/rock band from Genoa, Italy, active since 2010 and delivering fuzz-laden, groove-heavy riffs through a haze of overdriven amplification. The project channels the riff-worshipping spirit of the genre.

Metal band from Guadalajara in central Spain, active since 2013, evolving from early sludge/post-metal into heavier stoner metal/rock territory. Their stylistic shift reflects a move toward riff-driven heaviness.

J. D. Overdrive is a southern metal band with a stoner twist from Katowice, Poland, delivering groove-laden heavy music across four albums. Their releases including Wendigo and The Kindest Of Deaths blend the swagger of southern rock with the heavy fuzz of stoner metal, establishing them in the Polish heavy rock scene.

Jack and the Bearded Fishermen is a heavy noise rock band from Besancon, France, active since 2005 with five guitarists and a rhythm section. Their fifth album Naked (2025), released through Twenty Something, showcases two decades of evolution in their guitar-dense, textured approach to noise rock and post-hardcore.

Jadira is a metal band from Tallinn, Estonia, whose releases including Desires and The Mason showcase their approach to heavy music from the Baltic underground. The Estonian metal scene's unique character infuses their compositions with a cold, atmospheric quality distinct from their Scandinavian neighbors.

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.

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.