Apocrifo was a thrash metal band from Fortaleza, Brazil, whose lyrical focus centered on the great fallacies and contradictions of modern society. The band released the two-track demo "No Alvo" in 2014, delivering tightly wound, palm-muted thrash in the classic Brazilian tradition before splitting up.

Apofenia is an old-school death/thrash metal band from the city of San Luis, Argentina, formed in late 2015 and playing their first show in January 2016. The band released their debut demo "Peste" in July 2016, a five-track assault featuring tracks like "Descuartizado" and "Muerte" rooted in brutal, no-frills extreme metal. Driven largely by siblings Anabelle Escudero on drums and Gisselle Escudero on guitar and vocals, Apofenia became one of the more notable all-female extreme metal acts in Argentina's interior provinces.

Apokalyptic Raids is a black/death/thrash metal band from Rio de Janeiro, originally formed in 1998 as Apocalyptic Raids — a name drawn directly from a Hellhammer EP — before adopting the current spelling in 2001. Driven by guitarist and vocalist Leon "Necromaniac" Manssur, they have released a string of albums and splits since their debut "Only Death Is Real" (2001), channeling the proto-black metal ferocity of Hellhammer, Bathory, and Vulcano while collaborating with acts like Whipstriker and Atomic Roar.

Arcanjo is a Christian thrash metal band from Brasília, Distrito Federal, Brazil, with origins tracing back to 1994. The band's lyrical themes center on Christianity, perseverance, and redemption, and they released a split with Soul Factor in 2001 before a period of inactivity and subsequent reformation.

Ardid is a thrash metal band from the Florencio Varela area of Buenos Aires province, with a lineup including Marcelo Lopez on vocals and bass, Jorge "Costra" García on guitar, and Ricardo "Ricky" Rodriguez on drums. The band completed their album "Mundo en coma" in 2023, presenting it live at Zadar Club in Wilde. Their material draws on classic thrash influences while addressing themes rooted in the working-class neighborhoods of the southern Buenos Aires conurbano.

Arkhaikus was a thrash metal band from Presidente Prudente, São Paulo, Brazil, active from 2010 until their split-up and operating under several earlier names including Slackerness and Metaldier before settling on the final moniker. The band's lyrical themes centered on warfare, evil, and metal culture, fitting squarely within the aggressive thrash tradition of the Brazilian interior. They documented their live activity with a bootleg recording from a 2011 show in Santo Anastácio.

Arsênio is a thrash metal band from Foz do Iguaçu, Paraná, formed in 2012 in the tri-border city where Brazil meets Argentina and Paraguay. The band carries the aggressive, old-school thrash tradition of the Brazilian underground.

Artes Negras is a black/thrash metal band from Buenos Aires, Argentina whose lyrical themes revolve around paganism, death, and Argentine werewolf folklore (the Lobizón). Their debut album "Let There Be Death" was released on CD in 2004 and featured members performing under pseudonyms including Necromandus on vocals, Lordnatt and Nan Noctambulus on guitars, Hellbastard on bass, and Funeris on drums.

Assault is a speed/thrash metal band from Vitória da Conquista, Bahia, formed in 2021 and playing in the aggressive tradition of Brazilian thrash metal. Operating out of the interior of Bahia — a state better known for axé and forró than thrash — the band channels the raw, high-tempo aggression of the genre with themes rooted in misanthropy and anti-religious sentiment.