Group
- Obatron Productions9
- Obsidian Turtle5
- Ohio Men of the Red Chest18
- Ohio War Kings12
- Old Gamers Club2
- On The Lamb Games3
- One World By Night2
- Onyx Path Publishing6
- Onyx Path/White Wolf4
- Orc Stomp2
- Orion Township Public Library1
- Ottawa Red Shirts32
- Overworld Games5
- Ozarks RISING30
- PLAID HAT GAMES1
- PM Promotions1
- Paizo Inc.389
- Paladin Miniatures Studio17
- Palegain Press LLC3
- Palladium Books43