Extinct chapters
This page is dedicated in remembrance of all those Space Marine Chapters that are entirely and definitely very dead. This does not include chapters that fell to Chaos, so all those lost (wiped out, turned heretic, barely survived or still missing) during the Abyssal Crusade aren't listed here, for that see Judged. Special mentions to the 2 lost legions.
Astral Knights
Sacrificed their chapter to destroy the Necrons' World Engine in 926.M41.
Crimson Castellans
This chapter was fighting against renegades from their own chapter when a Tyranid Hive Fleet came by and ate them both.
Crimson Consuls
Seriously, don't put crimson in the chapter's title if you want it to live. This chapter was taken out piece by piece in a series of freak accidents which were only discovered to have been arranged by the Alpha Legion when their battle-brothers' subliminal programming was activated to wipe out the Chapter leadership.
Dark Paladins
Annihilated by Necrons while investigating Jarrman Prime.
Emperor's Swords
Destroyed by the Alpha Legion who contaminated their recruiting pool and implanted subconscious triggers in their recruits.
Emperor's Swords again
Based on Bellicas, which turned out to be a tomb world. Begin face-palming.
Fire Hawks
Lost in the warp. Surviving members may or may not make up the Legion of the Damned.
Fists Exemplar
Discretely replaced the completely depleted Imperial Fists with a handful of other volunteers from the Imperial Fists' successors after The War of The Beast, with their records purged after it was discovered that the remaining members of the chapter had detected to the Iron Warriors.
Flame Falcons
Declared excommunicate traitoris by the Inquisition and officially extinguished by Grey Knights. Few survived.
Imperial Fists
Destroyed in War of The Beast, secretly replenished with Fists Exemplar.
Knights of Blood
Sacrificed to a man in a desperate effort to protect Baal from the Tyranid and Khorne-Daemon smackdown. Due to their reputation as borderline-heretics, it wasn't rebuilt in the Ultima Founding.
Knights of Eternity
Another chapter presumed to have been eaten by the Kraken.
Obsidian Glaives
Chapter destroyed by the Red Waagh. Detailed in Sanctus Reach campaign.
Sable Swords
Extinct by M41. Refounded to replace Astral Knights.
Soul Drinkers
Declared extinct. After becoming disillusioned with the Imperium and turning renegade, they were finally brought to trial and ended up sacrificing themselves to fend off a daemon army, the three loyalist survivors exiled themselves to the warp along with their Chaos turned brother.
Tiger Claws
Lost in the warp, surviving members absorbed by their founders, the Astral Claws, who later caused the Badab War and turned traitor as the Red Corsairs after escaping following the defeat.
Unnumbered Sons
The initial reserve of Primaris Marines before they were entirely reorganised into existing chapters or formed new or legacy chapters. Not technically extinct, but no longer exists as a functioning unit.
Wolf Brothers
Succumbed to the instabilities of their gene-seeds. Any survivors are now feral wulfen.