Insurmountable Obstacle is a death metal/grindcore/hardcore/punk band from Kulmain, Germany, active since 1992, making them one of the oldest extreme crossover acts in the Bavarian countryside. Over three decades, the band has fused multiple extreme genres from their base in rural Upper Franconia.

Insurrect are a black/death metal and crust band from the United Kingdom, formed in 2023. Their releases including Nomadic War Machine blend extreme metal with politically charged crust punk under a Red Black Resistance banner.

Integritlie are a black/thrash metal band from the Mondsee-Unterach area of Upper Austria who sing and write in the local Austro-Bavarian dialect, lending their aggressive thrash framework an unusual linguistic identity. Their 2017 self-titled album features tracks like "Todgeweiht" and "Flammeninferno," marrying raw black metal energy to driving thrash riffs.

Intended Execution is a brutal death metal band from Weiden in der Oberpfalz, Germany, active since 2014, delivering punishing extremity from the Upper Palatinate region of Bavaria. The band channels maximum brutality through a relentless, uncompromising approach.

Interdiction is a thrash/death metal band from Dortmund, Germany, active since 2003, merging thrash metal's velocity with death metal's heaviness from the heart of the Ruhr Valley. Over two decades, the band has refined their dual-genre assault into a tight, devastating package.

Interface are a grindcore and death metal band from Belfast, Northern Ireland, formed in 2017. They bring ferocious grinding extremity to the Northern Irish underground.

Interfectorem were an old school death metal band from Eferding, Upper Austria, active from 2011 to 2014 before splitting up. The five-piece played classic death metal in the vein of early 1990s European acts and opened the Sick Midsummer Austria festival in 2013.

Black/death metal band from Murcia in southeastern Spain, active since 2012. Their Latin name — meaning 'slain' — channels extreme metal from the Mediterranean coast.

Interior of Death is a death metal band from Proszowice, Poland, active since 2009 and delivering uncompromising extremity through crushing riffs and guttural vocals. The project channels the relentless brutality of the genre.