I will update this list going forward as I need to make sure what counts as a properly canon chapter
As of now, the criteria I’m using is that a chapter is canon as long as they have been mentioned in a Black Library novel, the Chapter Approved Section of White Dwarf, The Successor Chapters compendium Or a 40k Codex
ULTRAMARINE
-Howling Griffons
-Avenging Sons
-Mortifactors
-Illuminators
-Silver Templars
-Patriarchs of Ulixis
-Aurora Chapter
-Sons of Orar
-Black Consuls
-Obsidian Jaguars
-Sons of Antaeus
-Inceptors
-Doom Legion
-Silver Skulls
-Libators
-White Consuls
-Genesis Chapter
-Scythes of the Emperor
-Novamarines
- Dark Sons (successors of the Novamarines)
- Angels of Fury (trained by the Novamarines, consider themselves their successors because of this)
-Mentors
-Sons of Guilliman
-Emperor’s Spears
-Castellans of the Rift
-Marines Errant
-Iron Snakes
IMPERIAL FISTS
-Subjugators
-Death Strike
-Crimson Fists
-Hammers of Dorn
-Celestial Lions
-Executioners
- Skull Bearers (Successors of Executioners)
- Iron Champions (Successors of Executioners)
-Black Templars
- Silver Guard (successors of Black Templars)
-Hospitallers
-Red Templars
-Sons of Dorn
-Soul Drinkers (new ones)
-Iron Templars
-Brotherhood of Dorn
-Celestials
SPACE WOLVES
-Wolf’s Spear
BLOOD ANGELS
-Sable Guard
-Blood Legion
-Angels Encarmine
-Flesh Tearers
-Sable Knights
-Ichor Guard
-Lamenters
-Atlantean Spears
-Blood Templars
-Absolvers
-Flesh Eaters
-Blood Drinkers
-Cruor Blades
-Golden Sons
-Dragons Ardent
-Angels Numinous (created after the splitting of the Blood Eagles)
-Red Seraphs (created after the splitting of the Blood Eagles)
SALAMANDERS
-Dark Krakens
-Black Dragons
-Dragon Spears
-Covenant of Fire
-Black Vipers
WHITE SCARS
-Solar Hawks
-Storm Lords
-Dark Hunters
-Sons of Jaghatai
-Wrathhost
-Marauders
-Rampagers
-Destroyers
-Mantis Warriors
-Jade Scorpions
-Astral Bears
IRON HANDS
-Brazen Talons
-Rust Oxens
-Red Talons
-Sons of Medusa
DARK ANGELS
-Angels of Absolution
-Guardians of the Covenant
-Angels Arisen
-Disciples of Caliban
-Angels of Defiance
-Coweled Wardens
-The Unnamed
RAVEN GUARD
-Rift Stalkers
-Void Sabres
-Dark Eagles
-Death Spectres
-Raptors
-Repentant Brotherhood
-Angels of Penance
NO-KNOWN PARENT
-Clementine knights
-Angels of Damnation
-Twilight Magisters
-Farstalkers
-Angels of Fire
-Dictators
-Sons of Galathor
-Auric Patricians
-Blood Vipers
-Grey Giants
-Tormentors
-Celestial Guard
-Champions of Thanatos
-Marines Malevolent
-Doomsayers
-Regents of Gheren
-Crusaders
-Accipiters
-Angel Guard
-Crimson Scythes
-Dark Hands
-Tormented
-Night Sentinels
-White Panthers
-Astral Spears
-Minotaurs
-Celebrants
-Colossi of Kronos
-Adulators
-Angels Eradicant
-Star Phantoms (some say they are Dark Angels, but it’s not yet confirmed)
-Benedictors
-Reparators
-Axes of the Emperor
-White templars
-Silent Vigil
-Tributors
-Silver Spectres
-Rhetors