Atomic Symphony were a progressive metal band from Zürich, Switzerland, formed in 2009 and initially operating as a symphonic metal act before shifting toward the polyrhythmic complexity of Dream Theater and Meshuggah. The band released three albums — "Redemption" (2015), "HYBRIS" (2022), and "Nemesis" (2023) — before announcing an indefinite hiatus in October 2023.

Atrophia Red Sun has evolved from melodic doom and death metal into progressive death and industrial territory from Kraków since 1997. Nearly three decades of reinvention from Poland's intellectual capital have produced one of the country's most stylistically adventurous extreme metal projects.

Atroposy was a progressive death metal band from Plovdiv, Bulgaria, active from 2019 to 2022. They released at least two tracks — "...And Thou was The Usurper" and "Bitter Joy" — through their Bandcamp page before splitting up.

Atrorum is a progressive black metal band from Munich, Germany, active since 1998, pushing the boundaries of black metal through complex song structures and unconventional compositional approaches. With over a quarter century of activity, the band represents the long-running experimental edge of Bavaria's black metal underground.

London's ATVM operate at the intersection of black metal, death metal, and progressive complexity, weaving labyrinthine song structures through dissonant harmonies and shifting tempos. Since 2015, their intellectually demanding approach has established them as one of the UK capital's most ambitious extreme metal acts.

Audience is a progressive metal band from Lingen in Lower Saxony, Germany, formed in 2015, exploring the genre's characteristic interplay of complex compositions, dynamic shifts, and technical musicianship. The band brings progressive metal ambition to the Emsland region near the Dutch border.

Auerkallio blends progressive death metal with progressive rock from Tampere since 2011. Their Finnish-language name adds local identity to compositions that bridge the technical demands of death metal with the expansive possibilities of progressive rock.

Augury is a progressive metal band from Andernach on the Rhine in Germany, formed in 2018, navigating the genre's complex song structures and technical demands. The band operates from the historic Rhineland city, contributing to the progressive metal scene in the middle Rhine valley.

August Life explores heavy and progressive metal from the Netherlands since 2018. Their vitality-evoking name suggests the peak of summer — and of creative energy — channeled through technically ambitious compositions.