Cifer is a speed and thrash metal one-man project from São Paulo, Brazil, formed in 2018 by multi-instrumentalist Henrique Perestrelo, who has also played in bands such as Blasthrash, Flagelador, and Infected. The project draws on 80s and early 90s influences including Exodus, Kreator, Sodom, Accept, and Mercyful Fate, and released the debut album "The Summoning" in 2019.

Cihoze is a Brazilian death/thrash metal project based in the Brasília/Goiás area, formed in 2020. The duo — Igor "Skullthrash" Gomes on guitar and vocals and Iury "Stringbreaker" Morais on bass and drums — released their debut album "Pesadelo da Realidade" in July 2020, recorded at Witchtrap Studios in Brasília.

Cinical is a groove metal band from Mendoza, Argentina, founded by brothers Vaka and Bruno Allegretti alongside Warren Marino and Uriel Memoli. Their album Resurgir was produced by Andrés Giménez of Argentine metal legends A.N.I.M.A.L., giving the record a heavy, mid-tempo groove rooted in the Mendoza underground scene.

Cinnamun Beloved is a gothic metal band from Buenos Aires, Argentina, fronted by vocalist and keyboardist Sabrina Filipčić. The band released their debut album The Weird Moment in 2015, followed by Stain in 2018, blending gothic metal with symphonic and electronic elements in a style shaped by the Buenos Aires underground.

Cipriano is a raw black metal band from Curitiba, Paraná, Brazil, drawing on the primitive, speed-driven style of acts like Darkthrone, Judas Iscariot, and Satanic Warmaster. The project features members active in the Curitiba underground scene and released the demo "Servos de Berwick" through Balrogh Records, with lyrics entirely in Portuguese.

Circadia is a heavy metal and hard rock band from Catriel, Río Negro, Argentina, drawing on classic 1980s and 1990s metal influences. The band has released recordings including the singles Leonidas and the EP Sucesos, building a following in the Patagonian underground metal scene.

Circle of Fear is a gothic metal band from San Antonio de Arredondo, Argentina, whose name is taken from a HIM song. The band released the single Deep Emotional Modus Operandi, a dark and atmospheric piece that drew coverage from international metal media in early 2026.

Circulo Negro is an independent black metal band from Itaituba, Pará, Brazil, formed around 2013–2014. The band explores themes of witchcraft and satanism and released the demo "Supremacia Herege" in 2015, distributed through Brazilian underground distros such as Jazigo Distro.

Cirrhosis is a death metal band from Uberlândia, Minas Gerais, Brazil, originally formed in 1988 by members who also played in Sarcófago; after dissolving in 1993 they reformed in 2001 and signed with the legendary Cogumelo Records. The band released the full-lengths "Alcoholic Death Noise" (2002) and "Drinks From Hell" (2009), built around a booze-and-brutality lyrical identity rooted in the classic Brazilian extreme metal tradition.