Operador channel the frustrations of the Brazilian call-center grind into punishing thrash and heavy metal, with lyrics drawn directly from the monotony and dehumanization of telemarketing work. Their 2022 demo "Conexão Call Center" laid out the concept in eight tracks, and the re-recorded version released in 2023 sharpened the riffs while keeping the satirical edge intact.

Oppressus is a thrash metal band from Neiva, Huila, Colombia, formed in 2011. Their debut full-length "Humanidad in Vitro" was released in 2017, with lyrics addressing social and political nonconformity, war, death, and destruction. The band remains active as an independent act on the Colombian underground metal scene.

Opressor are an independent death metal outfit from Curitiba who have been grinding out heavy, uncompromising material since 2013. Active and unsigned, they operate squarely within the brutal death metal tradition that the Paraná underground has quietly fostered for decades.

Optofobia is a grindcore band from Merida, Venezuela. Active since at least 2014, they have released a series of EPs including "Corporotocracia" (2014), "Existencia en decadencia" (2015), and "Hacia el matadero" (2019), as well as splits with international acts like Dalle Killers and Nastiness.

Originally active between 2004 and 2009, Opus Nokturne returned in 2024 with a heavier, darker orientation, blending black and death metal textures into a progressive framework. Their debut EP "Winds of Sand," released independently in June 2025, marks the project's reintroduction with a sound that leans into dense atmospherics and compositional ambition.

Founded in 2015 by vocalist Azi Dahaka, Opus Secretus pursues a Luciferian strand of black metal rooted in ritual atmosphere and occult doctrine. Their 2024 full-length "The Dissolution of the Flesh for the Awakening of the Luciferian Flame" was produced by Thiago Perdurabo and Azi Dahaka, with instrumentals recorded in Magé and vocals laid down at Espaço Lugar Nenhum in Rio de Janeiro.

Opus V bring together seasoned Brazilian heavy metal musicians for a dense, keyboard-driven brand of progressive metal that draws on classic prog and power metal equally. Their 2020 album "Universe of Truths" featured notable guests including Zakk Stevens of Savatage on vocals and Ricardo Confessori of Angra on drums, signaling the band's ambitions well beyond the local scene.

Orate are a stoner/grunge outfit from Santiago, Chile who have been active since 2004, drawing on grunge, indie rock, and stoner influences in their songwriting. They released a self-titled debut in 2004 and returned over a decade later with El Ave Madrina in 2017, an eight-track album that leans into hazy, groove-driven rock with Spanish-language lyrics.

Orate are a stoner/grunge outfit from Santiago, Chile who have been active since 2004, drawing on grunge, indie rock, and stoner influences in their songwriting. They released a self-titled debut in 2004 and returned over a decade later with El Ave Madrina in 2017, an eight-track album that leans into hazy, groove-driven rock with Spanish-language lyrics.