Ironbound is a crossover thrash metal band from Alagoinhas, Bahia, Brazil, featuring vocalist Angello, guitarist Kenion, bassist André, and drummer Raul. The band released several EPs including "Máquina da Morte" and "Possuídos Pelo Thrash," delivering aggressive Portuguese-language thrash rooted in the tradition of classic Brazilian extreme metal. They returned to activity in 2018 after a period of inactivity, continuing to represent the underground thrash scene of northeastern Brazil.

Irreverencia is a speed/thrash metal band from Santiago, Chile, active since 1995, whose lyrics address atheism and political themes. Their 2001 album Dadme la otra mejilla stands as a key release in their catalogue, and the band has remained active through releases on Santiago's Bolchevique Records.

Irritator was a thrash metal band from São Paulo, Brazil, formed in 2020 with a lineup of Renato Castro on vocals, Matheus Fortunato and Eduardo Covello on guitars, Rafael Savone on bass, and Lucas Prado on drums. The band recorded a self-titled demo featuring five tracks sung entirely in Portuguese, addressing themes of social chaos, political corruption, and inequality — drawing sonic comparisons to Sepultura and Pantera. Praised by Brazilian metal media outlet Whiplash.Net for their maturity and conviction, the band has since split up.

Isa Nielsen is a Danish-Brazilian heavy metal guitarist and vocalist based in São Paulo who began performing at age 13 and has built a career spanning major Brazilian stages. She has performed at Rock in Rio and opened for Tom Morello and John 5 at the Best of Blues and Rock festival before audiences of over 40,000, and has jammed live with Steve Vai. Her debut album "Break the Chains" showcases her dual role as a lead guitarist and vocalist in the classic heavy metal and hard rock tradition.

Isaurian is a shoegaze-inflected doom and post-metal band from Brasília, Brazil, formed in 2017, whose sound fuses gloomy doom tonality with post-metal atmosphere and dreamy, layered textures. Their second album "Chains of Blue" (2020), released fully independently and produced by Kevin Ratterman — known for his work with Emma Ruth Rundle — featured vocalist Hoanna Aragão and was recorded in São Paulo. The band followed it with "The Pulsing Rush" in 2024, further developing their organic, evolving approach to heavy music.

Iscaron is a black metal band from Barranquilla, Colombia, active since 2009 and currently signed to Entropy Records. The project is driven by the multi-instrumentalist known as Bhaal and deals in themes of anti-Christianity, darkness, and war, with releases including the 2015 EP "El sueño de Erzebet" and the 2023 EP "La estela de la revelación".

Isen Son is a heavy and thrash metal band from Maringá, Paraná, Brazil, drawing influences from heavy, doom, and thrash metal traditions. The band recorded their debut EP "Evil" in December 2022 in Maringá, releasing it in February 2024 through Metal Archives and SoundCloud. They represent the growing underground metal movement in Brazil's interior, away from the better-known scenes of São Paulo and Belo Horizonte.

Isfet are a melodic black/death metal band from Florianópolis, Santa Catarina, Brazil. Drawing heavily on the Swedish melodic black metal tradition of the late 1990s, they released their debut full-length Shards from a Formless Past in October 2017, an eight-track record recorded at GERE Studios. Their lyrical themes revolve around misanthropy, occultism, and anti-cosmic philosophy.

Isolate are a death metal band from Brasília, Distrito Federal, Brazil. Influenced by acts such as Amon Amarth, Obituary, and Gorefest, the band released the EP Memories in the Ashes in February 2013, featuring members Luciano on vocals, Rodrigo and Carlos on guitars, Walisson on bass, and Júlio on drums. An earlier promo rehearsal demo, Soul Infector, circulated in 2008 and established the band's heavy, riff-driven approach.