| Title | Code | Date | Publisher | System (Setting) |
|---|
 I Am Providence | | 2014 | Self Published | I Am Providence |
| I Am the Fourth Wall | | 2019 | Slinky Gibbon Games | I Am the Fourth Wall |
 I Pray God Will Curse the Writer | | 2016 | Teapot Dome Games | I Pray God Will Curse the Writer |
| I Want to Play | FXC-07 | 2019 | Stygian Fox | Call of Cthulhu (Now) |
| I Want You to Kill the Ice Cream Man | | 2000 | Self Published | Call of Cthulhu (Now) |
| Iaa! Cthulhu! Fhtagn! | | 2016 | Sphinx Speileverlag | Iaa! Cthulhu! Fhtagn! |
| Ice Cream Man * | | May 2019 | Chaosium | Call of Cthulhu (Now) |
| Iconoclasts | APB8138 | 2022 | Arc Dream Publishing | Delta Green |
| Icons of the Mythos | | 2024 | Ad Infinitum Adventures | ICONS |
| An Ideal Society | | 2006 | Self Published | Call of Cthulhu (Now) |
| The Idol of Thoth | | Dec 2017 | Stygian Fox | Call of Cthulhu (Classic) |
| Igor Ichor Promo Card | | Mar 2009 | Steve Jackson Games | Munchkin |
| Ill Omens Art Pack | | Dec 2017 | Chaosium | Call of Cthulhu (Classic) |
| The Illumination of Aldebaran | | 2023 | Gallant Knight Games | Tiny Cthulhu |
 Imagine | 13 | Apr 1984 | TSR | Call of Cthulhu (Classic), None |
| Imagine | 28 | Jul 1985 | TSR | None, Call of Cthulhu (Classic), Daredevils |
 Imazine | 16 | 1987 | Self Published | Call of Cthulhu (Classic) |
| The Immortal Minority | 2 | 1987 | Self Published | Call of Cthulhu (Classic) |
| The Impaler | | 1984 | Self Published | Call of Cthulhu (Classic) |
| The Impossible Chamber | | Jul 2024 | Chaosium | Call of Cthulhu (Regency) |
 Impossible Landscapes | APU8145 | 2021 | Arc Dream Publishing | Delta Green |
| In a Different Light | cr3001 | 2011 | Cthulhu Reborn | Call of Cthulhu (Classic) |
| In Dark and Lonely Waters | | Jul 2024 | Chaosium | Call of Cthulhu (Now) |
| In Darkness We Wait | | Apr 2024 | Chaosium | Call of Cthulhu (Now) |
| In From the Cold * | | 2017 | Golden Goblin Press | Call of Cthulhu (Classic) |
 In Memory of Day | CT27 | 2009 | Fantasy Flight Games | Call of Cthulhu LCG |
 In Search of Sanity | PZO90109 | 2016 | Paizo Publishing | Pathfinder |
| In Strange Aeons: Lovecraftian Numenera | MCG014P | 2013 | Monte Cook Games | Numenera |
| In Strange Seas | | May 2023 | Chaosium | Call of Cthulhu (Regency) |
| In Strange Seas: The Regency Cthulhu Naval Compendium | | Oct 2023 | Chaosium | Call of Cthulhu (Regency) |
| In the Clutches of Chaos * | AHC34 | 2019 | Fantasy Flight Games | Arkham Horror: The Card Game |
| In the Depths of Silverstring | | 2020 | Mundus Infinitos | In the Depths of Silverstring |
| In the Dread of Night | CT28 | 2009 | Fantasy Flight Games | Call of Cthulhu LCG |
| In the Shadow of the Horns | | Dec 2021 | Chaosium | Call of Cthulhu (Classic) |
| In the Shadows | CHA2357 | 1995 | Chaosium | Call of Cthulhu (Classic) |
| In the Violet Hour | | | Golden Goblin Press | Call of Cthulhu (Invictus) |
| In Too Deep * | AHC53 | 2020 | Fantasy Flight Games | Arkham Horror: The Card Game |
| In Xanthic Terms | | Oct 2023 | Chaosium | Call of Cthulhu (Now) |
| The Incredible Dr Quinn | | Jan 2022 | Chaosium | Call of Cthulhu (Now) |
| The Incriminating Letter | | 2003 | Self Published | Call of Cthulhu (Classic) |
| Indescribable Underworlds | | 2025 | Everything Epic Games | Secrets of the Lost Tomb |
| INDIGO: Advancement Points | | May 2024 | Chaosium | Call of Cthulhu (Now) |
| Indigo: After the End of the World | | Feb 2018 | Chaosium | Call of Cthulhu (Now) |
| The Infaernum of Cthulhu | | 2024 | Mind's Vision | Infaernum |
| Infestation | | Mar 2022 | Chaosium | Call of Cthulhu (Classic) |
| Infinite Gulfs of Darkness | | 2021 | Ludonova | Arkham Noir |
| Inglorious Victorians | | 2020 | Bendjinn | Call of Cthulhu (Gaslight) |
| Inheritance | FS03 | 2007 | Self Published | Call of Cthulhu (Rising) |
| Inheritance | | 2019 | Chaosium | Call of Cthulhu (Classic) |
| Inhuman Trafficking | | Sep 2023 | Xipe Totec Press | Call of Cthulhu (Now), Cthulhu Dark, Trail of Cthulhu, Cthulhu Obscura, Delta Green |
| Initiations of the Favored | CT42 | 2011 | Fantasy Flight Games | Call of Cthulhu LCG |
| Injury Cards | PELGY01IC | 2019 | Pelgrane Press | The Yellow King |
| Inncommers | | 2016 | Xipe Totec Press | Cthulhu Dark, Trail of Cthulhu, Delta Green, Call of Cthulhu (Now) |
| An Inner Call | | Sep 2020 | Chaosium | Call of Cthulhu (Classic) |
| An Inner Darkness | GGP2001 | 2020 | Golden Goblin Press | Call of Cthulhu (Classic) |
| The Inner Light | | Jan 2024 | Chaosium | Call of Cthulhu (Classic) |
| Innsmouth 32 | | 2020 | GameWick Games | Innsmouth 32 |
| The Innsmouth Conspiracy * | AHC52 | 2020 | Fantasy Flight Games | Arkham Horror: The Card Game |
| The Innsmouth Curse | | 2024 | Self Published | The Innsmouth Curse |
| The Innsmouth Cycle * | CHA6017 | 2006 | Chaosium | Call of Cthulhu (Classic) |
| Innsmouth Escape | TLC3401 | 2008 | Twilight Creations | Innsmouth Escape |
| Innsmouth Handout Pack | | 2021 | base113 Games | Call of Cthulhu (Classic) |
| Innsmouth Horror Expansion | VA57 | 2009 | Fantasy Flight Games | Arkham Horror |
| The Innsmouth Lighthouse | | 2009 | Self Published | Risus |
| Innsmouth Mystery | | 2023 | Self Published | Innsmouth Mystery |
| The Innsmouth Papers | | 2020 | Self Published | The Innsmouth Papers |
| Innsmouth Poster Maps | | 2015 | Lore Wise Games | Call of Cthulhu (Classic) |
| Innsmouth: The Stolen Child | | 2022 | Blue Fox Publishing | Innsmouth: The Stolen Child |
 Inperium Romanum | CHA23115map | 2009 | Chaosium | Call of Cthulhu (Invictus) |
| Insanitarium | | 2019 | Chaosium | Call of Cthulhu (Classic) |
| Intellect Devourer | 1 | 1987 | Self Published | Call of Cthulhu (Classic) |
| Intellect Devourer | 7 | Jun 1988 | Self Published | Call of Cthulhu (Now) |
| Interface | 6 | 1992 | Prometheus Publishing | Call of Cthulhu (Cyberpunk) |
| Interface 19.40 | MUH050027AC | 2015 | Modiphius Entertainment | Interface Zero, Call of Cthulhu (Achtung!), Savage Worlds (Achtung!) |
| The Intermountain Matrix Newsletter | 5 | Mar 1991 | Self Published | Call of Cthulhu (Classic) |
| Interregnum | 30 | May 1999 | Self Published | Call of Cthulhu (Classic) |
| Intersections | | 2016 | Xipe Totec Press | Cthulhu Dark, Trail of Cthulhu, Delta Green, Call of Cthulhu (Now) |
| The Interstellar Colonial Marine Corps | | 2008 | Self Published | Call of Cthulhu (Rising) |
| Into a Dark Heart | | Aug 2021 | Chaosium | Call of Cthulhu (Classic) |
| Into Tartarus | CT51 | 2011 | Fantasy Flight Games | Call of Cthulhu LCG |
| Into the Gothic | | Oct 2023 | Chaosium | Call of Cthulhu (Classic) |
| Into the Maelstrom * | AHC58 | 2021 | Fantasy Flight Games | Arkham Horror: The Card Game |
| Into the Unknown | | Apr 2022 | Chaosium | Call of Cthulhu (Strange Aeons) [2052] |
| The Invasion * | | 2021 | Petersen Games | Cthulhu Wars |
| Invasive Procedures | PELG09 | 2011 | Pelgrane Press | Trail of Cthulhu |
| Inversion | | Feb 2024 | Chaosium | Call of Cthulhu (Now) |
| Investigator Expansion Pack | | 2020 | Purple Meeple Games | Cultistorm |
| Investigator Mug Set | CHA9303 | | Chaosium | None |
| Investigator Passports | | 2019 | base113 Games | Trail of Cthulhu, Call of Cthulhu (Classic) |
| Investigator Promo Cards * | | 2017 | Fantasy Flight Games | Elder Sign |
| Investigator Sheets | CHA5111 | 1993 | Chaosium | Call of Cthulhu (Classic) |
| Investigator Weapons Volume 1: The 1920s and 1930s | 60-IHB01 | 2012 | Sixtystone Press | Call of Cthulhu (Classic) |
| Investigator Weapons Volume 2: Modern Day | 60-IHB02 | 2015 | Sixtystone Press | Call of Cthulhu (Now) |
| Investigator Weapons Volume 3: Gaslight Era | 60-IHB03 | Jan 2023 | Sixtystone Press | Call of Cthulhu (Gaslight) |
| The Investigator's Companion | | 2020 | M T Black Games | Whispers in the Dark |
| Investigator's Guide to the Secret War | MPS01031CS | 2013 | Modiphius Entertainment | Savage Worlds (Achtung!), Call of Cthulhu (Achtung!) |
| Investigator's Guide to the Secret War * | MUH51740 | 2019 | Modiphius Entertainment | Call of Cthulhu (Achtung!) |
| Investigator's Handbook | CHA23136 | 2015 | Chaosium | Call of Cthulhu (Classic) |
| Investigators | | 2019 | Petersen Games | Cthulhu Wars |
| Investigators Kit * | CHA5102 | | Chaosium | Call of Cthulhu (Classic) |
| The Investigators of Arkham Horror * | NAHCE1 | 2016 | Fantasy Flight Games | Arkham Horror: The Card Game |
| Investigators of Horrors! | | Oct 2019 | Chaosium | Call of Cthulhu (Classic) |
| Invisible Fires | | Dec 2023 | Librarians and Leviathans | Cthulhu Eternal |
| An Invitation in Yellow | | Feb 2018 | Chaosium | Call of Cthulhu (Classic) |
| Invitation Only | WitD1 | 2020 | Saturday Morning Scenarios | Whispers in the Dark |
| Ira Incensa | | Mar 2021 | Chaosium | Call of Cthulhu (Classic) |
| Ire of the Void * | EAH12 | 2017 | Fantasy Flight Games | Arkham Horror |
| Ire of the Void * | NAH12 | 2017 | Fantasy Flight Games | Arkham Horror: The Card Game |
| Irrational Express * | | 2003 | Self Published | Call of Cthulhu (Classic) |
| The Island * | SKP01110 | 2011 | Skirmisher Publishing | Call of Cthulhu (Classic) |
| The Island | | Jul 2024 | Chaosium | Call of Cthulhu (Classic) |
| Island 256 | | May 2019 | Chaosium | Call of Cthulhu (WWII) |
| Island Getaway | | Dec 2023 | Modiphius Entertainment | Achtung! Cthulhu |
| The Island of Dagon | | 2021 | One Shot RPG | One Shot RPG |
| The Island of Ignorance | GGP1301 | 2013 | Golden Goblin Press | Call of Cthulhu (Classic) |
| Island of Ignorance | | 2023 | Just Crunch Games | The Cthulhu Hack |
| Isle of Madness | | Dec 2017 | Chaosium | Call of Cthulhu (Classic) |
| It Came From Cthulhu | | 2012 | Planet Pulp Productions | Pulp Adventure |
| It Came from the Wild Blue Yonder | | 2010 | Self Published | It Came from the Wild Blue Yonder |
| The Ithaqua Cycle | CHA6021 | 1998 | Chaosium | Call of Cthulhu (Classic) |
| Ithaqua the Wind-Walker | | 2023 | CMON Limited | Cthulhu: Death May Die (Fear of the Unknown) |
| The Itinerant Hotel | | May 2021 | Chaosium | Call of Cthulhu (Classic) |