| ID | Name | Type |
|---|---|---|
| #22489 | Ocean Software France | P |
| #10508 | Ocean Software Ltd | P |
| #10509 | Ocean-Imagine Hellas | Z |
| #10510 | Octavio Campos Barroso | + |
| #10511 | Octavio Montagud Ballester | + |
| #10512 | Octocon Data | ? |
| #15913 | Octogram | ? |
| #17582 | Octopus Computing Holidays | C |
| #10513 | Octopus Software | Z |
| #22000 | Odd Job | + |
| #22211 | Oddball Software | P |
| #10514 | Oddworld Inhabitants Inc | Z |
| #10515 | Odin Computer Graphics Ltd | P |
| #10516 | Odisea Software | Z |
| #10517 | Odrick | ? |
| #10518 | Odyssee | ? |
| #10519 | Odyssey Computing | P |
| #10520 | Ofer Ben-Ami | ? |
| #21589 | Offence | U |
| #10521 | Offeyre | ? |