Asilo was a Buenos Aires sludge, drone, and doom metal collective that built a catalog of slow, crushing releases across the 2010s, including the split with Neh Czneg (2013), Comunión (2014), and Desintegración (2019). Their approach leaned toward extended, corrosive compositions that placed them firmly within the heavier end of Argentina's underground doom scene.

Askaroth is a black metal trio from Isla de Maipo, Chile, featuring Odal (bass, vocals), Cruelbuth (guitar), and drummer Nilsson Arriagada (also known as Beleth), who have been active since the early 2010s with releases including the demo "Unholy Demian" (2011), the cassette "Lejania" (2012), and a split with Nocturnal Delirium titled "Memories" (2012) through Depressive Illusions Records. The band issued a self-titled full-length album in March 2022.

Aske is a black/death metal band from São Carlos, São Paulo state, operating in the Brazilian extreme metal underground since 2018. Their approach sits firmly in the raw, aggressive end of the black-death spectrum, with releases distributed independently through Bandcamp.

Asmodeus is a thrash/death metal band from Fortaleza, Ceará, with roots tracing back to the city's early heavy metal underground. After a long dormancy, the band was reactivated around 2015 to mark the 30th anniversary of the Tempestade Metálica festival — a cornerstone event in Ceará's metal history — and have since recorded two studio albums: Parabellum (2018) and Continuamos a Falar de Flores (2021).

Asmodina was a melodic death/black metal band from Teresina, Piauí, a city with a small but determined extreme metal scene in Brazil's northeastern interior. The project drew on the melodic death and black metal aesthetics common to the early 2000s Brazilian underground before splitting up.

Asper is a heavy metal band from Porto Alegre, Rio Grande do Sul, active since 2018 in one of Brazil's most established regional metal scenes. Porto Alegre has long been a hub for traditional and extreme metal in southern Brazil, and Asper operates within that tradition as an independent act.

Asphalt Grieving is a black/death metal act from Santiago, Chile, who debuted in January 2024 with the EP "Lack of Certainty," released by Black Legion Records as a limited clear CD edition of 300 copies worldwide. Later in 2024 they released a second EP, "Transgression of the Quantum Self: Tertiary Magnitude," featuring session drums by Krzysztof Klingbein and three tracks totaling approximately 24 minutes.

Asphyxiated is a death metal band from Salvador, Bahia, formed in 2022 and representing a newer generation of extreme metal emerging from Brazil's northeastern coast. Operating as an independent act, the band adds to Salvador's growing underground metal presence.

Aspidis is a dissonant black/death metal band from Jaraguá do Sul, Santa Catarina, founded in 2012. Their 2017 EP Reborn From Darkness and their more recent album Intruding Voices (2025) reflect a dense, abrasive approach to the genre with roots in the dissonant death metal current popularized by acts like Ulcerate and Gorguts.