Cork's Sirocco blend folk and heavy metal with a name referencing the hot Mediterranean wind since 2020. Their incorporation of traditional elements into metal reflects Ireland's rich folk music heritage.

Sisko play thrash metal from Frankfurt, channeling old-school velocity and aggression from the Hessian financial capital. Active since 2016, they represent the ongoing vitality of thrash in one of Germany's major cities.

Sister formed in Jönköping, Sweden in 2006, building a hard-edged sleaze rock sound that drew equally from 1970s punk and 1980s Hollywood glam metal. The band signed with Metal Blade Records and released their debut album Hated in 2011, followed by Disguised Vultures in 2014. Described by critics as occupying a space between The Misfits and Guns N' Roses, Sister cultivated a raw, street-level aesthetic at odds with the more polished Swedish sleaze contemporaries. The band later released Vengeance Ignited independently in 2021 and returned with The Way We Fall in 2025.

Sisters of Suffocation is an all-female death metal band from Eindhoven, Netherlands, founded in 2014 by vocalist Els Prins and guitarist Simone van Straten with the explicit goal of building a women-fronted extreme metal act. The band released their debut EP Brutal Queen independently in 2016, followed by their full-length Anthology of Curiosities (2017) and Humans Are Broken (2019) on Napalm Records. Their straightforward death metal approach, free of novelty or genre dilution, earned them performances at major European festivals alongside recognition as one of the more authentic acts to emerge from the Dutch extreme metal underground in the 2010s.

Sisyfos deal in death metal from the Arctic city of Rovaniemi, their mythological name (the man condemned to roll a boulder eternally) reflecting the relentless, repetitive crushing of their sound. Formed in 2019, they bring Sisyphean extremity to Lapland.

Death metal/hardcore crossover band from Zonhoven in Belgian Limburg, formed in 2023. Their fusion of death metal brutality and hardcore aggression creates a punishing hybrid rooted in the extreme underground of the Flemish countryside.

Galway's Six Down have been dealing in sludge metal since 2000, making them one of Ireland's longest-running heavy acts. A quarter-century from the west coast has forged a sound of oceanic weight and relentless undertow.

Six Months of Sun channel stoner metal from Geneva, building hazy, riff-driven compositions that evoke sun-baked heaviness. Their sound draws on the psychedelic end of the doom/stoner spectrum with a Swiss sensibility.

Six Point Six play heavy metal from Bietigheim-Bissingen in Baden-Wurttemberg, tracing their roots back to 1977 when the band was originally founded. Their four-decade heritage makes them one of the longest-running acts in the southwestern German metal scene.