Nuclear Trauma is a solo crossover thrash project born during the pandemic, built around raw and unfiltered riffing with lyrical content focused entirely on warfare and armed conflict. Early recordings including the ISMO demo, Religious War, and Remains of War establish a stripped-down sound in the tradition of classic American crossover, with no frills and no concessions.

Nuclear War is a thrash metal band from San Salvador, El Salvador, formed in 2015. Their sole release is the EP War Dance (2018), a short blast of war- and death-themed thrash recorded while the band was active. The band has been on hold since 2018.

Formed by Thomas and Edu in the mid-2000s, Nuclëar Fröst channel Swedish d-beat hardcore, Japanese crust, and 1980s thrash into a politically charged war-metal hybrid. Their 2009 album Nuclear Winter Gloom and the 2014 self-titled EP show a band equally indebted to Discharge and early Bathory, with antifascist and nuclear-apocalypse lyrics running throughout. They have also appeared on several international splits alongside acts from the global crust underground.

One of the more savage relics of the late-1980s underground, Nuctemeron played a brutal and primitive blackened noise-grind that positioned them alongside other uncompromising Brazilian extreme acts of the era. Their 1990 demo Industrial Pollution and the captured chaos of the 1991 live tape Last Massacre represent the entirety of their output, later compiled on the FOAD Records release Posers Mutilation 1989–1991.

Nudimmud draw on Mesopotamian mythology and demonology for both their name and their thematic framework, weaving those ancient references into coldly atmospheric black metal. Their 2012 split with Natimorto on Hammer of Damnation, titled Anointed in Angel Blood, introduced tracks like Melammu Xul and Daughters of Lot — occult-inflected compositions that show a band more interested in ritualistic weight than in speed.

Nulla Ratio is a solo black metal project from Curicó, Maule, conceived, recorded, and mixed entirely by the single member Iatros. The project debuted with Fire Wombs in June 2021, followed by Phases in November 2022, the latter released on limited cassette through Cognitio Mors Vincit, with themes centered on death.

Num is a groove metal band from Buenos Aires, Argentina, whose sound blends thrash, djent, and alternative metal influences into a dense, rhythmically focused attack. The band released three albums in rapid succession — NUM (2014), Desarreglos (2015), and Lo Que Sangra (2017) — building a reputation in the Argentine underground metal scene.

Nunca Mas is an Argentine heavy metal band formed in 2000, whose music draws on left-wing political themes, social history, and collective memory — a stance reflected in their name, meaning "Never Again" in Spanish. The band earned early recognition in the local scene with a contribution to the 2002 Hermética tribute compilation released by Dejesú Records.

Não Inação is a crossover thrash trio from Mauá whose debut EP Saúde Mental Deteriorada packs five tracks of politically charged aggression into under eight minutes, drawing equally from São Paulo hardcore punk and classic thrash. Tracks like "Falta de Ar" and "Desespero" hit themes of mental deterioration and social pressure with the blunt economy the genre demands.