B on Reason is a heavy/thrash metal band from Pernambuco, Brazil, formed in 2021. The project spans multiple releases including albums titled The Mission, Endless Siege, and The Empire of Lost Souls, carving out a self-described universe of metal, game, and multimedia content. Their sound sits in the classic heavy metal and thrash tradition rooted in the Northeast Brazilian underground.

Baba de Sheeva is a thrash/crossover band from Goiânia, Goiás, Brazil, bringing the fast and irreverent spirit of the genre to the Central-West metal scene. Formed with themes revolving around life, religion, drinking, and weed, the band released the CD-R É Triste O Destino Da Maioria Dos Homens in 2011 and has remained an active presence in the Goiânia underground. Their sound blends the aggression of old-school thrash with the punk energy of crossover.

Backstroke is a thrash metal band from Brasília, Brazil, formed in 2019. Operating out of the capital's underground scene, the band channels straightforward, aggressive thrash in the Bay Area and Brazilian tradition. They remain active as an independent act in the Brasília metal community.

Bacteria is a heavy/thrash metal band from San José, Entre Ríos, Argentina, active since 1999. The band appeared on the 2009 compilation "2dos. Puro Metal" released by Kodigo Rojo Records out of Concordia, Entre Ríos, one of the few regional metal labels documenting the underground scene in that province.

Bad Resilience is a grindcore and noisecore project from São Paulo, Brazil, founded in mid-2024 by musician Rodrigo Chenta. The project fuses diminutive riffs with raw blast-beat grind, drawing lyrical themes from Christian theology — including kenosis, ordinances, and martyrdom — with lyrics in both English and Spanish. Their debut album Mutilated Head (2024) arrived alongside the single Stoning, establishing a deliberately brutal and theologically charged identity.

Bad Salad is a progressive metal band from Brasília, Brazil, formed in 2007 by brothers Thiago Campos (guitar) and Felipe Campos (bass) alongside drummer Caco Gonçalves. Their debut album Uncivilized (2012) earned international critical acclaim for its complex songwriting and songs regularly exceeding ten minutes, drawing comparisons to Dream Theater and Opeth; the follow-up EP Puzzled appeared in 2013. The band was handpicked by Mike Portnoy to perform on the Progressive Nation at Sea cruise in 2014, one of the few Brazilian acts to achieve that distinction.

Badtrip Surfdeath is an instrumental power trio from São Paulo, Brazil, active since 2008 and coined the term 'surfdeath' to describe their collision of hardcore, grind blasts, black metal riffs, and psychedelic textures. The trio of Rodrigo Chã (guitar), Manéu Junqueira (bass), and Marcus Dentão (drums) released their self-titled debut in 2011 followed by Badtrip Surfdeath II in 2013, both recorded in São Paulo. Their entirely wordless approach lets the genre-blurring density of the music speak for itself.

Bael was a black metal band from Santo André, São Paulo, Brazil, formed in 2024 and short-lived. Emerging from the Greater São Paulo underground, the band pursued the raw and nihilistic black metal aesthetic before splitting up the same year they were founded. Their brief existence places them within the dense web of São Paulo-area black metal acts working in the underground tradition.

Bagronk is a death/black metal band from the southern suburbs of Greater Buenos Aires, Argentina, with roots going back to an early 2000s formation. The band recorded the demo "Death and Blood Valley" and has built a persistent presence in the Argentine underground extreme metal scene across multiple active periods.