Infierno is a black metal band from San Salvador de Jujuy, Argentina, with roots going back to 1989 under the name Delirio Infernal before reactivating under the current name in 2013. The band is one of the oldest extreme metal acts from the northwestern Argentine province of Jujuy, and released the rehearsal recording "Ensayo 99" in 1999. Their themes span destruction, hatred, and Satanism, and the band is noted on Metal Archives for having used at least five distinct logos across their history.

Infinity Horror was a death metal band from Assis, São Paulo, Brazil, formed in 2014 and later disbanded. Their debut recording, the demo Celestial Profanation, was released on February 17, 2014, and recorded at Estudio Improviso. The band operated within Brazil's underground old-school death metal circuit during their brief active period.

Infinity of Thoughts is a one-person atmospheric and depressive black metal project from Osasco, São Paulo, Brazil, founded in 2021 by the artist known as Valak. The project blends black metal with ambient and atmospheric elements, drawing influence from acts such as Summoning, Nargaroth, and Thy Light. Releases include the debut album When the Winter Ends (2021) and Aeterna Tormenta (November 2024), both available on Bandcamp.

Infortunia is a one-man raw black metal project based in Palhoça, Santa Catarina, Brazil, created in 2025 by the sole member known as Count Boulanger. The project has released two recordings, Aquilo Que Nós Vemos and Dissonance of Chaos, channeling a stripped-back, lo-fi approach to the genre.

Infortuno is a death/doom and hardcore band from Piracicaba, São Paulo, formed in 2022, featuring vocalist Bruno Lucas, guitarist Rodrigo Santos, bassist Bruno Reina, and drummer Bruno Lanza. The band released their debut EP, Decadent Vindication, in January 2023, a five-track record blending sludgy riffs and doomy breakdowns with NYHC-influenced drum grooves. They followed it in 2024 with Covenant of Dissent, a split release with Counterraid.

Inglorious Basterds is a heavy and power metal band from Indaiatuba, São Paulo, Brazil. The band released their debut full-length album, Inglorious Hearts, in 2023, a five-track record praised for its melodic riffs, cohesive bass work, and polished production.

Inheritours is a death metal band from Caxias do Sul, Rio Grande do Sul, Brazil, formed in 2014. The band is noted for their drummer Mateus Michelon, who became recognized beyond the local scene and went on to join the band Losna.

Inhibidor is a heavy metal band from Rosario, Argentina, formed in 2020 by Alberth Páez. Their debut album "Vértigo" was released in January 2022 and featured guest contributions from members of established Argentine metal acts including Horcas, Tren Loco, and Serpentor, reflecting the band's connections across the country's heavy metal scene. The album includes a cover of the classic RIFF song "En la Ciudad del Gran Río" alongside original material.

Inhuman Entity was a brutal death metal band from southern Chile, formed around 2016–2017 by vocalist Raul E. Gonzalez, guitarist Gonzalo Sanchez (also of Carniceria Grotesca), and drummer Manu Acevedo (also of Hail Caligula). The band released their sole EP Kingdom of False Divinity in May 2017 through Rotten Music, a four-track slab of brutal death metal with goregrind elements drawing on both old-school and contemporary influences from the international extreme metal underground.