Masamsed is a sludge and post-metal band from Lyon, France, formed in 2020. They blend crushing sludge with post-metal's atmospheric expansiveness.

Mass Culture is a sludge and post-metal band from Athens, Greece, formed in 2012. They blend crushing sludge with post-metal's atmospheric dynamics from the Greek capital.

A post-metal and progressive metal band from Charleroi in Wallonia, Massive Therapy build dense, textured compositions that favor atmosphere and dynamic range over conventional song structures. The band have released recordings through Bandcamp, contributing to Belgium's thriving post-metal underground that has produced internationally recognized acts from the Walloon region.

Matote is a stoner, doom, and post-metal band from Badalona, Spain, formed in 2018. They merge stoner metal's fuzzy heaviness with doom's crushing weight and post-metal's atmospheric dynamics.

Maunah is a doom and post-metal band from Denmark, formed in 2025. They blend the crushing weight of doom with post-metal's atmospheric expansiveness and dynamic range.

Maunra are a blackened sludge and post-metal band from Vienna, Austria, who released their debut full-length 'Monarch' in September 2022 after five years of developing their sound. The album — recorded, mixed, and produced by Hannes Mottl, and mastered at Tonmeisterei Oldenburg — spans seven tracks that the band describes as 'a journey between the realms of decay and becoming.' Unlike many post-metal acts, Maunra anchor their sound firmly in riff worship rather than pure atmosphere.

Mausōleion is an atmospheric sludge and post-metal band from Leeds, England, formed in 2014. They craft expansive, textured compositions blending atmospheric sludge with post-metal dynamics.

Mayon is a sludge/post-metal band from Opava, Czech Republic, formed in 2018. Their sound inhabits the heavy, atmospheric territory where crushing sludge riffs meet the expansive dynamics and textural layering of post-metal.

A Belgian instrumental post-black metal project whose name is the Roman numeral for 1978, MCMLXXVIII describe their music as "wordless hymns to decay" and "raw, atmospheric aural sonic landscapes carved from shadows." Their albums The Sacred Rot and Wordless Hymns to Decay establish a bleak, minimalist aesthetic that forgoes vocals entirely in favor of texture and atmosphere.