Jagged Vision is a metallic hardcore band from Oslo, Norway, whose album Death Is This World (2017) was recorded by Phillip Cope at Jam Room Recording Studio and mastered by Brad Boatright at Audiosiege. Their crushing sound draws comparisons to Kylesa, early Mastodon, and High On Fire, delivering hardcore sludge with inventive riffs.

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.

Jahvl is a stoner rock band from St. Gallen, Switzerland, who released their self-titled debut album in 2024. Their nine-track record features extended compositions that range from heavy psychedelic jams to crushing riff-driven passages, establishing them in the Swiss heavy rock scene.

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.

Jena is a southern metal band from Brescia in northern Italy, formed in 2013 and describing themselves as a southern metal band from northern Italy. After nearly dissolving in 2018, they reconstituted with a new lineup and have since released Graboid (2021) and Outlaw (2023), delivering groove-heavy, riff-driven southern metal.

JJax is the solo project of Julien Jacquemond from Chambery, France, a veteran of several metal bands including Inner Visions, Further Dimension, and Dead Season. His solo work channels his decades of experience as a vocalist, composer, and multi-instrumentalist into original metal compositions with strong melodic hooks.

Jointhugger is a Norwegian heavy psychedelic doom rock band active since 2012, self-described as hashtronauts of the heavy playing cosmic, psychosonic doom rock straight from the fjords. Their trilogy of albums including Surrounded By Vultures (2021), composed by Nico Munkvold and recorded live at Stone Bone Cross Studio, channels deep fuzz and occult heaviness.

Jumping Jack is a French stoner rock trio from Nantes, delivering organic melodies built on a heavy rock wall since their debut Cows and Whisky (2009). They gained international exposure through a 25-date European tour in 2013 and have shared stages with Orange Goblin, Nashville Pussy, and Mustasch across three albums.

Jurassic Leaf is an instrumental doom/sludge/stoner metal band from Lille, France, whose album Groovosaur (2016) delivers six tracks of crushing, groove-oriented instrumental metal. Their prehistoric-themed compositions have earned praise as an instrumental juggernaut of captivating, eye-melting chugs.