Symphonic and melodic black metal band from Governador Valadares, Minas Gerais, formed in 2003 and previously signed to Avernus Records. Their music centers on anti-Christian and atheist themes, placing them within the philosophically provocative wing of Brazilian black metal; their orchestral arrangements and melodic sensibility set them apart from the rawer extreme metal acts that dominated Minas Gerais in the same era.

Atheris is a progressive and symphonic metal project from Buenos Aires led by Julian Muller, released through the Amniote Editions label and known for conceptually linked releases including ZRS-1: Instant Molting 1.0 and ZRS-2: Instant Molting 2.0 in 2019, followed by the Maculata EP in 2022. The project takes its name from a genus of venomous bush vipers, with track and album titles drawn from herpetology, underscoring a distinctive conceptual identity.

Athkan is a groove and thrash metal band from Salta, Argentina, formed in 2013 by guitarist Gustavo Díaz and bassist Sergio Ruiz. Drawing on the post-thrash heaviness of Pantera and Meshuggah, the band released two records in 2013 — the album Walking Through Fear and the compilation Simbiosis — with vocalist Mauro Espínola and drummer Eduardo Fernández rounding out the lineup.

Athus Cerimonae is a Brazilian black metal and dark ambient duo — Anatole (vocals, guitar, keyboards) and Angellus (bass, vocals) — whose music explores existential metaphysics and occult writing. Since their 2022 debut "Foedera Naturae," the project has released a series of albums weaving multilingual lyrics in Portuguese, English, and Romanian through atmospheric, ritualistic compositions.

Atila is a heavy metal band from Posadas, Misiones, Argentina, considered one of the pioneering metal acts of the province. The band — built around vocalist Sergio Toledo, guitarist Javier Duarte, and bassist Cristian Guaglianone — released their debut album Azote de Dios in 2017, followed by a second record, Mal Negocio, blending classic heavy metal with updated material spanning two decades of the band's history.

Atomic Fear was a death metal band from Timóteo, Minas Gerais, with roots tracing back to 2007 before the band reconstituted in the early 2010s. The group released the EP "Globaritarian" in 2013 and earned a foothold in the regional underground scene with politically charged lyrics delivered over aggressive death metal, performing at festivals including Grito do Rock in their home city before eventually splitting up.

Atomic Head was a speed metal band from Santiago, Chile, formed in 2004 by guitarist and vocalist SEbG with a focus on Bay Area thrash influences. The band released a self-titled five-track EP in 2006 and their only full-length album, March of the Urban Zombies, in 2014 before disbanding.

Atomic Roar is a thrash metal and metalpunk band from Rio de Janeiro, formed in 2003, featuring Victor Whipstriker of the punk outfit Whipstriker on bass alongside Vinícius Hellpreacher, Victor Poisonhell, and Léo Witchcaptor. The band deals in raw, street-level thrash with strong punk crossover energy, documented across four studio albums — "School of Lust" (2006), "The Warfare Merchants" (2009), "Atomic Freaks" (2011), and "Never Human Again" (2017) — as well as numerous split releases with bands from the global underground.

Atomic Thrash is a thrash metal band from Rio de Janeiro, formed in 2014 and currently on hold. Operating within the city's active underground thrash scene, the band plays aggressive, old-school thrash metal in the tradition that Rio de Janeiro — a foundational city for Brazilian extreme metal — has long cultivated.