Over the years, the Final Fantasy series has garnered not only the numbered entries and their sequels, but also the numerous other products - spin-offs, novelizations, manga... This list tries to give a picture of what the series includes besides just the main games.
Main Series
Final Fantasy I
Final Fantasy II
Final Fantasy III
Final Fantasy IV
Final Fantasy V
Final Fantasy VI
Final Fantasy VII
Final Fantasy VIII
Final Fantasy IX
Final Fantasy X
Final Fantasy XI
Final Fantasy XII
Final Fantasy XIII
Final Fantasy XIV
Final Fantasy XV
Final Fantasy XVI
Direct Sequels and Prequels
Final Fantasy I
Stranger of Paradise
(see also Dissidia series)
Final Fantasy IV
Interlude
The After Years
Final Fantasy V
Legend of the Crystals
Final Fantasy VII
Advent Children
Before Crisis
Crisis Core
Dirge of Cerberus
G-Bike
First Soldier
Remake
Rebirth
Ever Crisis
Final Fantasy X
Final Fantasy X-2
Final Fantasy XII
Revenant Wings
Final Fantasy XIII
Final Fantasy XIII-2
Lightning Returns
Final Fantasy XV
A King's Tale
Brotherhood
Kingsglaive
Monster of the Deep
Comrades
The Tactics Series
Main Series
Final Fantasy Tactics
Final Fantasy Tactics Advance
Tactics A2: Grimoire of the Rift
Final Fantasy Tactics S
Spinoffs
Crystal Defenders
Crystal Defenders+
Vanguard Storm
The Crystal Chronicles Series
Main Series
Crystal Chronicles
Ring of Fates
Echoes of Time
Crystal Bearers
Spinoffs
My Life as a King
My Life as a Darklord
The Dissidia Series
Dissidia
Dissidia 012 duodecim
Dissidia NT
Opera Omnia
Type Series
Final Fantasy Type-0
Final Fantasy Agito
The Awakening
Explorers Series
Final Fantasy Explorers
Explorers Force
Theatrhythm Series
Theatrhythm
Curtain Call
All-star Carnival
Final Bar Line
Legend Series
World Series
World of Final Fantasy
Meli-Melo
Brave Exvius Series
Brave Exvius
War of the Visions
Other Spinoffs
The 4 Heroes of Light
Mobius
Record Keeper
The Spirits Within
Final Fantasy Unlimited
Social and Casual Spinoffs
Airborne Brigade
All the Bravest
Artniks
Artniks Dive
Pictlogica
World Wide Words
Final Fantasy XI Universe
Expansion Discs
Rise of the Zilart
Chains of Promathia
Treasures of Aht Urhgan
Wings of the Goddess
Seekers of Adoulin
Story Expansion Packs
A Crystalline Prophecy
A Moogle Kupo d'Etat
A Shantotto Ascension
Battle Expansion Packs
Vision of Abyssea
Scars of Abyssea
Heroes of Abyssea
Other Expansions
Rhapsodies of Vana'diel
Voracious Resurgence
Spinoffs
Grandmasters
Final Fantasy XIV Universe
Remake
A Realm Reborn
Expansion Discs
Heavensward
Stormblood
Shadowbringers
Endwalker
Final Fantasy XV Universe
Note that direct sequels and prequels are listed in their own section.
Spinoffs
A New Empire
War for Eos
In-universe Games
Justice Monsters Five
King's Knight
Card Games
Trading Card Game
Tetra Master
Triple Triad
Manga and Comics
Beyond the Boundless Sky
Final Fantasy I Manga
Final Fantasy Type-0 Manga
The Ice Reaper
Legend of Eternal Wind
Lost Stranger
Unlimited After
Novels and Short Stories
After Spiral
The After Years Novelization
The Bonds of Two
Change the World-series
Chronicles of Light
The Dawn of the Future
Episode i
Episode Zero
Final Fantasy IV Novelization
Final Fantasy XI Novel Series
Final Fantasy XIV Novels
Fragments After
Fragments Before
In the Mist-Shrouded Capital
The Kids Are Alright
Labyrinth of Nightmares
Maiden Who Traveled the Planet
Memories like the Sunshine
Memory of Heroes
One Day in the Garden's Classroom
On the Way to a Smile
Our World
Parting Ways
The Price of Eternity (Final Fantasy X-2.5)
The Spirits Within novelization
Tracer of Memories
Traces of Two Pasts
Unlimited After
Will
Miscellaneous
Case of Denzel (anime short)
Final Fantasy VII Snowboarding (mobile game)
Final Fantasy Tactics Advance (cd drama)
Final Fantasy Unlimited - With You (mobile game)
Final Fantasy Unlimited on PC (PC game)
Last Order (anime short)
Lost Episode (mobile game)
Unlimited After 2 (cd drama)
Unlimited Before (cd drama)
The Chocobo Series
Chocobo no Fushigina Dungeon
Chocobo's Dungeon 2
Chocobo Racing
Chocobo Stallion
Dice de Chocobo
Hataraku Chocobo
Chocobo Land: A Game of Dice
Final Fantasy Fables: Chocobo Tales
Chocobo de Mobile
Final Fantasy Fables: Chocobo's Dungeon
Chocobo to Mahou no Ehon: Majo to Shoujo to Gonin no Yuusha
Chocobo Panic
Chocobo's Crystal Tower
Chocobo no Chocotto Nouen
Chocobo Racing 3D
etc
Others
Non-FF FFs
Vagrant Story
Would-be FFs
Fortress
Agni's Philosophy