Grisvelos is a one-man black/death metal project from Osorno, Los Lagos, Chile, created by Alfredo Torres, who also plays bass and backing vocals in the black/thrash band Degotten. The project debuted in August 2020 with the full-length "Desperatio," a nearly 50-minute album drawing from the influence of Morbid Angel, Immolation, and Marduk while channeling the band's description of Osorno as a cold, decadent city into music that blends ferocity with melodic, nostalgic atmosphere.

Grobr. is a solo doom metal project based in Jundiaí, São Paulo, Brazil, formed in 2025. The project is entirely self-produced by a single multi-instrumentalist who handles everything from composition to mixing, and has released the album Doomsday Clock alongside the standalone track Aether.

Grosstracktor is a groove metal band from Lota, Bio-Bío, Chile. The band's name references the Grosstraktor prototype medium tanks built by German manufacturers Rheinmetall-Borsig, Krupp, and Daimler for the Weimar Republic in violation of the Treaty of Versailles.

Grotesque Impalement is a death metal band from Olavarría, Buenos Aires province, founded as a duo by brothers Riky (drums) and Daniel Krotter (guitar and vocals), with Manuel Rossetti later joining on bass. The band released a self-titled EP in 2017 before dropping their debut full-length, Morbid Fetal Creation, in December 2021, recorded under EscabioDeth Records.

Guerreiros Headbangers is a black/thrash metal band from São Paulo, Brazil, who released their debut album Eras em Guerras, Mundo em Caos in 2024 along with singles including Memento Mori and Noite Através da Noite. The band has shared the stage with internationally recognized acts such as Bulldozer, Enforcer, Skull Fist, Nocturnal, and Witchtrap.

Guilhotina was a thrash metal band formed in 2008 in Presidente Prudente, São Paulo, Brazil. The band released a self-titled debut album in September 2008, an eight-track record available on Bandcamp. They have since split up.

Guillotine is a thrash/death metal band from Santo André, São Paulo, Brazil. Their album Metal in the Vein (2007) was recorded at Studio Cativeiro in Santo André and includes a hidden cover of Death's "Defensive Personalities." The band has been noted as a notable addition to the international thrash metal scene.

Gulag is a Brazilian avant-garde and depressive black metal solo project based in São Paulo, with all instrumentation, vocals, and composition handled by Matheus Cornely. The project released Fantasia in 2023, described as a departure toward sober black metal and dungeon synth aesthetics, incorporating a cover of Nocturnal Depression's "Nostalgia." The project also released Death and Its Roses and the Black Flag single on Bandcamp.

Gurkhorg is an atmospheric black metal band from Coquimbo, Coquimbo Region, Chile, formed in 2024. They are one of several atmospheric black metal acts active in the Coquimbo scene alongside local bands such as Aume and Sunvher.