| Title | Code | Date | Publisher | System (Setting) |
|---|
 U Mad Bro? | | 2016 | Prettiest Princess Games | U Mad Bro? |
 Ubar | | | Self Published | Call of Cthulhu (Classic), Call of Cthulhu (Gaslight) |
| Ubbo-Sathla Promo Card * | | 2015 | Fantasy Flight Games | Elder Sign |
 Ulthar | | Apr 2023 | Chaosium | Call of Cthulhu (Dreamlands) |
| Ulthar: No Man May Kill a Cat | | Oct 2023 | Xipe Totec Press | Cthulhu Dark, Trail of Cthulhu, Cthulhu Obscura, Delta Green, Call of Cthulhu (Dreamlands) |
| Ultima Thule | | Jun 2020 | Chaosium | Call of Cthulhu (Classic) |
| The Unapproachable | | 2020 | Old Bones Publishing | Mythras |
 Unaussprechlichen Katzen | CatDel02 | 2014 | CATTHULHU.com | Call of Cthulhu (Cathulhu) |
| Unaussprechlichen Klutzen | | 2011 | Bully Pulpit Games | Fiasco Classic |
| The Unbearable Likeness | FXC-01 | Jun 2019 | Stygian Fox | Call of Cthulhu (Now) |
 The Unbound Book | 0 | Aug 2002 | Unbound Publishing | Call of Cthulhu (Classic) |
| The Unbound Book | 1 | Oct 2003 | Unbound Publishing | Call of Cthulhu (Classic) |
| The Unbound Book | 2 | Aug 2005 | Unbound Publishing | Call of Cthulhu (Classic) |
| Unboxing | | Aug 2021 | Chaosium | Call of Cthulhu (Classic) |
| The Uncanny Curse of Sekhmet | | Jun 2020 | Self Published | Risus, Call of Cthulhu (Classic), Broken Compass, GURPS |
| Unconventional Diplomacy | CB71208 | 2014 | Cubicle 7 | Call of Cthulhu (Laundry) |
| Undead | | 2016 | Epic Level NPC | Pathfinder |
| Undead Wizard * | | 2015 | Pleasant Company Games | Ancient Terrible Things |
| Under a Grey Sun | | 2016 | Self Published | Lovecraftesque |
| Under a Winter's Snow | FXC-09 | 2020 | Stygian Fox | Call of Cthulhu (Classic) |
| Under Dark Waves | AHB05 | 2020 | Fantasy Flight Games | Arkham Horror |
| Under the Chalk | | Feb 2025 | Chaosium | Call of Cthulhu (Strange Aeons) [1976] |
| Under the Deep | | 2013 | Self Published | Call of Cthulhu (Classic) |
| Under the Dunes | | Mar 2023 | Chaosium | Call of Cthulhu (Classic) |
| Under the Frozen Grove | | Jun 2021 | Chaosium | Call of Cthulhu (Classic) |
| Under the Gun | MUH052303 | 2021 | Modiphius Entertainment | Achtung! Cthulhu |
| Under the Pyramids | EH05 | 2015 | Fantasy Flight Games | Eldritch Horror |
| Under the Red Light | | Nov 2022 | Chaosium | Call of Cthulhu (Classic) |
| Under the Tree | | Mar 2021 | Chaosium | Call of Cthulhu (Now) |
| Undertow of Madness | | 2020 | Grimlord Games | The Everrain |
| Undimensioned and Unseen * | AHC06 | 2017 | Fantasy Flight Games | Arkham Horror: The Card Game |
| Undying Leaders | CHA0343 | 2007 | Chaosium | Call of Cthulhu (Classic) |
| Unexplored | MUH0010350 | Feb 2024 | Modiphius Entertainment | Achtung! Cthulhu |
| Unexplored: Swamp and Tundra | MUH0010372 | May 2024 | Modiphius Entertainment | Delta Green |
| Unfathomable | UNF01 | 2021 | Fantasy Flight Games | Unfathomable |
 Unfortunate Events Deck | CHA23139-KD3 | 2016 | Chaosium | Call of Cthulhu (Classic) |
| Unfortunate Events Deck * | CHA23184-KD3 | Sep 2024 | Chaosium | Call of Cthulhu (Classic) |
| Unholy Presents | | 2016 | Atlas Games | Lost in R'lyeh |
| Unicum: H P Lovecraft Edition | | 2014 | Sphinx Speileverlag | Unicum |
| Union and Disillusion * | AHC33 | 2019 | Fantasy Flight Games | Arkham Horror: The Card Game |
| Unique High Priests | | 2016 | Petersen Games | Cthulhu Wars |
| The Unknowable Box | | 2023 | CMON | Cthulhu: Death May Die (Fear of the Unknown) |
| Unknown | | | Self Published | Call of Cthulhu (Classic) |
| Unlimited | CAO1306-1 | 1997 | Chaosium | Mythos |
| Unlocking Dice: Dice Vermiis Mysteriis | | 2020 | Petersen Games | Unlocking Insanity |
| Unmasked Rally | | 2016 | Xipe Totec Press | Delta Green, Trail of Cthulhu, Cthulhu Dark, Call of Cthulhu (Now) |
| The Unmasking | | 2013 | Self Published | Call of Cthulhu (Delta Green) |
| Unnameable | CW-U25 | 2019 | Petersen Games | Cthulhu Wars |
 The Unnamed | 3 | | Self Published | Call of Cthulhu (Classic) |
| Unnatural Mystic | | 2018 | Pleasant Company Games | Ancient Terrible Things |
| Unofficial Mythos Adventure Archive | | | Self Published | Mythos |
| Unpleasant Dreams | AG1331 | 2012 | Atlas Games | Gloom |
| The Unravelling | | Jul 2019 | Dark Trapezohedron Productions | Call of Cthulhu (Gaslight) |
| Unremembered | | Jan 2019 | Chaosium | Call of Cthulhu (Now) |
| The Unremembered | | Jul 2023 | Chaosium | Call of Cthulhu (Classic) |
| Unseen Forces | SL15 | 2013 | Fantasy Flight Games | Elder Sign |
| Unseen Masters | CHA2384 | 2001 | Chaosium | Call of Cthulhu (Classic) |
| Unseen Unraveling | GA-BOOK013 | 2023 | Penguin Comics | None |
| Unspeakable Box | DMD-KS01 | 2019 | CMON | Cthulhu: Death May Die |
| Unspeakable Cults: Azathoth | UC001 | 2019 | d20pfsrd.com Publishing | Pathfinder |
| Unspeakable Letters Promo Card | | 2014 | Playroom Entertainment | Unspeakable Words |
| The Unspeakable Oath | 1 | Dec 1990 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 2 | May 1991 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 3 | Aug 1991 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 4 | Dec 1991 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 5 | May 1992 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 6 | Aug 1992 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 7 | Jan 1993 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 8/9 | Jun 1993 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 10 | Jan 1994 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 11 | Jan 1995 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 12 | Jun 1995 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 13 | Jan 1996 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 14/15 | 1997 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 16/17 | Mar 2001 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 18 | Dec 2010 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 19 | Mar 2011 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 20 | Jun 2011 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 21 | Jul 2012 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 22 | Jan 2013 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 23 | Aug 2013 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath | 24 | Jul 2014 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Oath * | AHC13 | 2017 | Fantasy Flight Games | Arkham Horror: The Card Game |
| The Unspeakable Oath | 25 | Jul 2018 | Pagan Publishing | Call of Cthulhu (Classic) |
| The Unspeakable Pages | CT57 | 2012 | Fantasy Flight Games | Call of Cthulhu LCG |
| Unspeakable Tales | | 2004 | Fantasy Flight Games | Call of Cthulhu CCG |
| The Unspeakable Vault | SJG1455 | 2008 | Steve Jackson Games | Munchkin |
| Unspeakable Words | PLE26100 | 2007 | Playroom Entertainment | Unspeakable Words |
| Unspeakable Words Deluxe Edition | | 2015 | Playroom Entertainment | Unspeakable Words |
| Unstill Waters | | 2011 | Reality Blurs | Savage Worlds (Realms of Cthulhu) |
| Unusual Suspects | | Aug 2025 | Human Gorilla | Call of Cthulhu (Now) |
| Unveiled Threats | WDF23600 | 2011 | WildFire Games | CthulhuTech |
| Unwanted | | 2016 | Uber Goober Games | Unwanted |
| Up on the Rooftop | | Nov 2025 | Chaosium | Call of Cthulhu (Now) |
 Upgraded Ritual and Doom Tracks | CW-U11 | 2017 | Petersen Games | Cthulhu Wars |
| Urban Exploration Innsmouth 2020 | PE30 | 2023 | PE30 | None |
| Ursa Major | | Feb 2025 | Chaosium | Call of Cthulhu (Classic) |
| The Usurpers | | Jul 2024 | Chaosium | Cthulhu Eternal |
| USX Modern Day Heroes: Cthulhu Monsters | | 2008 | RAFM | USX Modern Day Heroes |
| Utatti Asfet | CHA2360 | 1996 | Chaosium | Call of Cthulhu (Classic) |