To the best of my knowledge, the table below contains all the official subclasses for fifth edition dungeons and dragons (as of May 24, 2020). There are several Unearthed Acana (UA) subclasses, buy I have not included these because UA is not considered official fifth edition content.
These are the books where the subclasses can be found.
Eberron Rising from the Last War (ERftLW), Explorer’s Guide to Wildmount (EGtW), Guildmasters’ Guide to Ravnica (GGtR), Player’s Handbook (PHB), Sword Coast Adventure’s Guide (SCAG) and Xanathar’s Guide to Everything (XGtE)
| Artificer |
| Alchemist |
ERftLW (p. 58) |
| Artillerist |
ERftLW (p. 59) |
| Battle Smith |
ERftLW (p. 60) |
| Barbarian |
| Path of the Ancestral Guardian |
XGtE (p. 9) |
| Path of the Battlerager |
SCAG (p. 121) |
| Path of the Berserker |
PHB (p. 49) |
| Path of the Storm Herald |
XGtE (p. 10) |
| Path of the Totem Warrior – Bear |
PHB (p. 50) |
| Path of the Totem Warrior – Eagle |
PHB (p. 50) |
| Path of the Totem Warrior – Elk |
SCAG (p. 122) |
| Path of the Totem Warrior – Tiger |
SCAG (p. 122) |
| Path of the Totem Warrior – Wolf |
PHB (p. 50) |
| Path of the Zealot |
XGtE (p. 11) |
| Bard |
| College of Glamour |
XGtE (p. 14) |
| College of Lore |
PHB (p. 54) |
| College of Swords |
XGtE (p. 15) |
| College of Valor |
PHB (p. 55) |
| College of Whispers |
XGtE (p. 16) |
| Cleric |
| Arcana Domain |
SCAG (p. 125) |
| Death Domain |
DMG (p. 96) |
| Forge Domain |
XGtE (p. 18) |
| Grave Domain |
XGtE (p. 19) |
| Knowledge Domain |
PHB (p. 59) |
| Life Domain |
PHB (p. 60) |
| Light Domain |
PHB (p. 60) |
| Nature Domain |
PHB (p. 61) |
| Order Domain |
GGtR (p. 25) |
| Tempest Domain |
PHB (p. 62) |
| Trickery Domain |
PHB (p. 62) |
| War Domain |
PHB (p. 63) |
| Druid |
| Circle of Dreams |
XGtE (p. 22) |
| Circle of the Land |
PHB (p. 68) |
| Circle of the Moon |
PHB (p. 69) |
| Circle of the Shepherd |
XGtE (p. 23) |
| Circle of Spores |
GGtR (p. 26) |
| Fighter |
| Arcane Archer |
XGtE (p. 28) |
| Battle Master |
PHB (p. 73) |
| Cavalier |
XGtE (p. 30) |
| Champion |
PHB (p. 72) |
| Echo Knight |
EGtW (p. 183) |
| Eldrich Knight |
PHB (p. 74) |
| Purple Dragon Knight |
SCAG (p. 128) |
| Samurai |
XGtE (p. 31) |
| Monk |
| Way of the Drunken Master |
XGtE (p. 33) |
| Way of the Four Elements |
PHB (p. 80) |
| Way of the Kensei |
XGtE (p. 34) |
| Way of the Long Death |
SCAG (p. 130) |
| Way of the Open Hand |
PHB (p. 79) |
| Way of the Shadow |
PHB (p. 80) |
| Way of the Sun Soul |
XGtE (p. 35)
SCAG (p. 131) |
| Paladin |
| Oath of the Ancients |
PHB (p. 60) |
| Oath of Conquest |
XGtE (p. 37) |
| Oath of the Crown |
SCAG (p. 132) |
| Oath of Devotion |
PHB (p. 85) |
| Oath of the Oathbreaker |
DMG (p. 97) |
| Oath of Redemption |
XGtE (p. 38) |
| Oath of Vengence |
PHB (p. 87) |
| Ranger |
| Beast Master |
PHB (p. 93) |
| Gloom Stalker |
XGtE (p. 41) |
| Horizon Walker |
XGtE (p. 42) |
| Hunter |
PHB (p. 93) |
| Monster Slayer |
XGtE (p. 43) |
| Rogue |
| Arcane Trickster |
PHB (p. 97) |
| Assassin |
PHB (p. 97) |
| Inquisitive |
XGtE (p. 45) |
| Mastermind |
XGtE (p. 46)
SCAG (p. 135) |
| Scout |
XGtE (p. 47) |
| Swashbuckler |
XGtE (p. 47)
SCAG (p. 135) |
| Thief |
PHB (p. 97) |
| Sorcerer |
| Divine Soul |
XGtE (p. 50) |
| Draconic Bloodline |
PHB (p. 102) |
| Shadow Sorcery |
XGtE (p. 50) |
| Storm Sorcery |
XGtE (p. 51)
SCAG (p. 137) |
| Wild Magic |
PHB (p. 103) |
| Warlock |
| The Archfey |
PHB (p. 108) |
| The Celestial |
XGtE (p. 54) |
| The Fiend |
PHB (p. 109) |
| The Great Old one |
PHB (p. 109) |
| The Hexblade |
XGtE (p. 55) |
| The Undying |
SCAG (p. 139) |
| Wizard |
| School of Abjuration |
PHB (p. 115) |
| School of Bladesinging |
SCAG (p. 141) |
| School of Chronurgy Magic |
EGtW (p. 184) |
| School of Conjuration |
PHB (p. 116) |
| School of Divination |
PHB (p. 116) |
| School of Enchantment |
PHB (p. 117) |
| School of Evocation |
PHB (p. 117) |
| School of Graviturgy Magic |
EGtW (p. 185) |
| School of Illusion |
PHB (p. 118) |
| School of Necromancy |
PHB (p. 118) |
| School of Transmutation |
PHB (p. 119) |
| School of War Magic |
XGtE (p. 59) |
Some official books also contain re-skins. These aren’t new subclasses but present some different options for some official subclasses. (Thank you to Matt Paluch).
| New Subclass |
Reskin of |
| Bard |
| College of Fochlucan (SCAG p.123) |
College of Lore (PHB) |
| College of New Olamn (SCAG p.123) |
College of Lore (PHB) |
| College of the Herald (SCAG p.124) |
College of Lore (PHB) |
| Druid |
| The Circle of Swords (SCAG p.127) |
Circle of Moon (PHB)
Circle of Land – Forest (PHB) |
| The Moonshea Circles (SCAG p. 127) |
Circle of Land – Coast, Forest, or Mountain (PHB) |
| Monk |
| Order of the Dark Moon SCAG (p. 129) |
Way of Shadow (PHB) |
| Order of the Hin Fist (SCAG p. 129) |
Way of the Open Hand (PHB) |
| Order of the Yellow Rose (SCAG p. 129) |
Way of the Open Hand (PHB) |
| Paladin |
| Order of the Companion (SCAG p. 132) |
Oath of Crown (SCAG)
Oath of Devotion (PHB) |
| Order of the Gilded Eye (SCAG p. 132) |
Oath of Devotion (PHB)
Oath of Vengeance (PHB) |
| Order of Samular (SCAG p. 132) |
Oath of the Crown (SCAG) |
| Any Class |
| Izzet League member (GGtR p.66) |
Any PC with a Spellcasting or Pact Magic class feature has access to League-only spells. |
Dungeon Master Assistance 
Thanks for this! Comparing it to my google doc now…
I like listing the re-skins as well so
Bard re-skins
College of Fochlucan (reskin of College of Lore, counts as PHB!) (SCAG)
College of New Olamn (reskin of College of Lore, counts as PHB!) (SCAG)
College of the Herald (reskin of College of Lore, counts as PHB!) (SCAG)
Druid re-skins
The Circle of Swords (reskin of either Circle of Moon or Circle of Land[Forest], counts as PHB!) (SCAG)
The Moonshea Circles (reskin of Circle of Land[Coast, Forest, or Mountain]. Counts as PHB!) (SCAG)
Monks
The Dark Moon Order (reskin of the Way of Shadow, counts as PHB) (SCAG)
The Hin Fist – Halfling Only! (reskin of the Way of the Open Hand, counts as PHB) (SCAG)
Order of the Yellow Rose (Way of the Open Hand reskin, PHB) (SCAG)
Paladin
Order of the Companion (Oath of Crown) (SCAG)
Order of the Gilded Eye (Oath of Devotion or Vengeance reskin PHB) (SCAG)
Order of Samular (Oath of the Crown) (SCAG)
(I had missed Rogue – Scout, thanks!!)
Wizard re-skin but close to a Sub Class due to background and Izzet League-only spells
Wizard – Invention (GGtR p66)
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Mike,
Not everyone reads the comments so I added this information to the post. Thank you very much.
A couple of observations:
The Order of the Hin Fist is not restricted to Halflings – “A few Hin Fist masters have established monasteries in lands outside Luiren, where the teachings available only to halfiings have been opened to students of other races who are willing to follow the path laid out by Yondalla.”
-and-
The Izzet League member can be any class, although I agree that it may work best for a Wizard.
Thanks again!
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Reblogged this on DDOCentral.
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Please update this with Tasha’s cauldron and mythic odysseys.
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Good idea.
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Nice!!
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