Reading, England's Sylosis, led by guitarist-vocalist Josh Middleton (who also plays in Architects), deliver a technically ferocious blend of melodic thrash and progressive death metal marked by Middleton's masterful guitar work and the band's relentless precision. Albums like 'Edge of the Earth' and 'A Sign of Things to Come' showcase riff writing that rivals the best in modern thrash, combining Bay Area speed with Scandinavian melodic sensibility. Despite Middleton's high-profile role in Architects, Sylosis remain a formidable creative outlet for his more technically demanding and extreme musical instincts.

Sylth crafts doom and post-metal from Toulouse, active since 2014. Their compositions unfold with patient deliberation, building from whispered tension to crushing, cathartic release through carefully orchestrated dynamic arcs.

Sylvaine is the solo project of classically trained Norwegian multi-instrumentalist Kathrine Shepard, founded in Oslo in 2013 and dedicated to the fusion of atmospheric black metal with shoegaze and post-rock — a style often termed 'blackgaze.' Shepard self-released her debut Silent Chamber, Noisy Heart in 2014, then released Wistful (2016), Atoms Aligned, Coming Undone (2018), and Nova (2022), earning a Norwegian Grammy nomination for Best Metal Album for the third — the first female musician to receive such a nomination in that category. Her work draws frequent comparisons to Alcest and Lantlôs.

Sylvania forge power metal from Valencia, channeling the genre's anthemic grandeur from Spain's third city. Emerging in 2025, they bring woodland-themed power to the Mediterranean metal scene.

Symakya plays symphonic and progressive metal from Nancy in Lorraine, active since 2011. Their ambitious compositions layer orchestral arrangements and complex structures over heavy guitar foundations, reflecting over a decade of creative refinement.

Symawrath evolved from symphonic black metal into industrial/electronic rock from the Catalan town of Constanti, tracing a dramatic stylistic transformation. Their Tarragona-area project reflects the genre-fluid spirit of modern Catalan heavy music.

Tomaszów Mazowiecki's Symbolical deliver death metal from the central Polish textile town since 2015. Their representational name and industrial-town origins channel the symbols of mortality into compositions of focused extremity.

Symbolizer play thrash metal from Copenhagen, channeling the genre's aggressive velocity from the Danish capital. Active since 2014, they bring symbolic fury to the Scandinavian thrash scene.

Tarnowskie Góry's Symetgal deliver death metal from the Upper Silesian town since 2019. Their enigmatic name and former silver-mining origins channel subterranean mystery into compositions of focused aggression.