List of Space Marine Chapters - M: NameOriginFoundingNotesMalevolentUnknownUnknownThe Malevolent is a Loyalist Space Marine Chapter of unknown Founding and origin.Mantis WarriorsMarauders8th FoundingThe Mantis Warriors, originally known as the Mantis Legion, is a Loyalist Space Marine Chapter believed to have been founded as part of the 8th Founding in 598.M35, created to help relieve the White Scars in monitoring and countering the many threats harboured by the Maelstrom Warp Storm in the Ultima Segmentum. The Mantis Warriors was one of the three Astartes Chapters that joined the Astral Claws in rebelling during the Badab War.MaraudersWhite ScarsSecond FoundingThe Marauders is a Loyalist Second Founding Successor Chapter of the White Scars according to the Apocrypha of Davio, written in the 33rd Millennium. The Mantis Warriors Chapter, which grew infamous during the Badab War, was created from the gene-seed stock of the Marauders.Marines AugustUnknownUnknownThe Marines August is a Loyalist Space Marine Chapter of unknown Founding and origin.Marines ErrantEagle Warriors23rd FoundingThe Marines Errant is a Loyalist, fleet-based Space Marine Chapter of Ultramarines genetic lineage created late during the 23rd Founding in the 37th Millennium, to repair the gap left in Imperial military forces by the loss of other Chapters.Marines ErrantorUnknownUnknownThe Marines Errantor is a Loyalist Space Marine Chapter of unknown Founding and origin.Marines ExemplarUnknownUnknownThe Marines Exemplar is one of the Loyalist Space Marine Chapters founded as part of the Astartes Praeses -- one of the 20 Chapters of Astartes mentioned in the ancient tome known as the Mythos Angelica Mortis that was created to defend the regions surrounding the Eye of Terror in the Segmentum Obscurus from the forces of Chaos. The Marines Exemplar are of an unknown Founding and origin.Marines MalevolentUnknownUnknownThe Marines Malevolent is a Loyalist Space Marine Chapter of unknown genetic origin founded in the 32nd Millennium. While loyal to the Emperor of Mankind and deeply dedicated to the eradication of all of the Imperium's enemies, it has at times shown a disturbing and callous disregard for the lives of the civilians of the Imperium as long as its mission objectives are obtained, which has brought it into conflict with the Salamanders Chapter as well as many other Imperial organisations, including the Inquisition.Marines MordantUltramarinesUnknownThe Marines Mordant was a Loyalist Space Marine Chapter of unknown Founding and a Successor Chapter of the Ultramarines. Raised in the 35th Millennium, the Marines Mordant were entrusted with guarding the rimward frontiers of the Maelstrom Zone, a task they performed alongside the Crimson Consuls, the Vindicators, and the Nova Legion. In the late 41st Millennium, all four Chapters were destroyed through the machinations of the Alpha LegionChaos Lord Quetzel Carthach.Marines VigilantUnknownUnknownThe Marines Vigilant were destroyed by the Crimson Fists after an unknown xenos or Warp encounter led them to refuse any futher combat duties.Marines VindicantUnknownUnknownThe Marines Vindicant is a Loyalist Space Marine Chapter of unknown origin and Founding. It played a major role in the scouring of the world of Vorlinghast in 981.M41, which had been overrun by Plague Zombies and the Death Guard Traitor Legion.Masters of ProtelusUnknownUnknownThe Masters of Protelus is a Loyalist Space Marine Chapter of unknown Founding and origin.MentorsUnknown26th FoundingThe Mentors, sometimes referred to in Imperial records as the "Mentor Legion," is a Loyalist Codex Astartes-compliant Space Marine Chapter. The Mentors were raised during the 26th Founding in 738.M41, making it one of the most recently founded Chapters in the Imperium of Man.MetamarinesUnknownUnknownThe Metamarines is a Loyalist Space Marine Successor Chapter of an unknown origin and Founding. The most renowned action of the Metamarines was their participation in the 13th Black Crusade in 999.M41.MinotaursUnknown21st FoundingThe Minotaurs is a savage Loyalist Space Marine Chapter of the 21st Founding whose origin remains unknown. The Minotaurs possess a reputation for being unusually xenophobic Astartes and unreliable combatants who do not work well with other Imperial military units.MortifactorsUltramarinesSecond FoundingThe Mortifactors is a Loyalist, Codex Astartes-compliant Second Founding Primogenitor Chapter founded during the 31st Millennium from Ultramarines gene-seed. The Mortifactors recruit from the austere Feral World of Posul, where the sun never rises on its frigid plains and its population of nomadic tribes are constantly in conflict with one another and practice cannibalism.