Kassiuz is a heavy metal band from Pico Truncado, Santa Cruz, Argentina, widely regarded as one of the pioneering acts of Patagonian heavy metal. The band self-released their debut demo in 2014, featuring tracks including "El Judas," "Redencion," "Primitivo Tehuelche," and "Patagonia," all recorded and mixed in their hometown. Their 2018 album Amigo de Metal featured a guest appearance by Carlos Cabral of veteran Argentine metal band Tren Loco on the title track.

Kataphero is a melodic death metal band from Natal, Rio Grande do Norte, Brazil, active since 2009, whose sound blends doom and black metal atmospheres with somber, introspective melodies. Their discography spans four albums: Life (2012), From Dust (2015), Veil of Illusions (2022), and From the Science of the Black Earth (2025), showing sustained creative output over more than a decade. The band's current lineup centers on brothers Paulo Henrique Santiago (vocals, guitar) and João Felipe Santiago (bass), alongside guitarist David Cantidio and drummer Rafael Borges.

Katarock is a thrash/death metal band from Florencio Varela, Buenos Aires, Argentina, originally formed in 1993 and later resuming activity from 2016 onwards. Their early releases include a five-track demo from 1994 and the promo single "Mutilador" from 2001. The band contributed the track "Bailanteros Q.E.P.D." to the 1997 Argentine metal compilation Nuevos Guerreros Vol. 1 on Yugular Records.

Katarsis Tenebris was a raw black metal band from Ponta Grossa, Paraná, Brazil, active from 2017 until splitting up around 2020. The band released the demo Cursed Plains of Mortality in May 2018, followed by the three-track demo Black KVLT in March 2019, exploring themes of darkness, occultism, and depression. Both recordings were self-released as digital albums under the banner of Brazilian raw black metal.

Katastrofy is a death metal band from Anchieta, Espírito Santo, Brazil, formed in 2006 and operating independently throughout their career. The band contributed the track "Blasphemy Or Die By Lie" to the Fortaleza Metal Vol. IV compilation in 2008, marking their earliest documented recording. Their lyrical themes center on blasphemy, death, and anti-religious subjects.

Kathartica is a heavy and stoner metal band from Rio de Janeiro, Brazil, formed in 2022 by guitarist Gabriel Policarpo and bassist Matheus Motta, with drummer Yael Torres and vocalist Jessé Monteiro completing the lineup. Drawing from classic heavy metal and a wide range of influences, the band blends weight and groove into their metallic sound. They are active on Bandcamp and Spotify as an independent act.

Katharzian is a symphonic and melodic black metal band from Manaus, Amazonas, Brazil, founded by vocalist Roosivelt Gomes and keyboardist Cecília Katrini, with a full lineup that includes guitarist Rômulo Toyoda, bassist Matheus Santos, and drummer Thiago Leão. The band released their debut album Purgatory in 2017 through Eternal Hatred Records, blending atmospheric black metal with symphonic and progressive elements. They performed a notable live set at the Anhangá Green Festival III in Manaus in August 2022, documented as a live release on Metal Archives.

Katástrofe is widely regarded as the longest-running thrash metal band in Campo Grande, Mato Grosso do Sul, with roots tracing back to 1994. Over their career the band has shared stages with major Brazilian metal acts including Dorsal Atlântica, Vulcano, and Ratos de Porão, and built their following on tracks such as "Labirinto da Morte" and "Pax Romana." The current lineup features Fernando Alemão on drums, Roberto on vocals, Faiska on bass, Eduardo Kadaver, and Lelo Reinoso on guitars.

Kausa y Efecto is a thrash/crossover band from Viña del Mar, Chile, playing in the tradition of the Valparaíso-region extreme metal scene. They released the album Estado de Control and have performed alongside acts such as Torturer, Acrostic, and Metastasis at Chilean metal festivals including Bay Area Assault.