| 1 | OCN | Octavia Airlines | IATA: O4, Callsign: Octaflight, Ceased operations. | F | AVCODES |
| 2 | OCN | Ocean GmbH | Callsign: Ocean, Subsidiary of Lufthansa. Name changed to EW Discover GmbH. | D | AVCODES |
| 3 | OCN | EW Discover GmbH t/a Eurowings Discover | IATA: 4Y, Callsign: Ocean, Subsidiary of Lufthansa. Name changed from Ocean GmbH. | D | AVCODES |
| 4 | OCN | O Air | | | ICAO1 |
| 5 | OCN | OLDE COLONY & NEW PORT | | | PWRC |
| 6 | OCNA | OCEAN AIR INTERNATIONAL INC | | | SCAC3 |
| 7 | OCNC | O C & CO | | | SCAC3 |
| 8 | OCNE | OCONEE TRANSFER SERVICE INC | | | SCAC3 |
| 9 | OCNE | OCEAN KAYAK | | | SCAC4 |
| 10 | OCNF | OCEAN-5 EXPRESS LINE INC. | | | SCAC3 |
| 11 | OCNH | OCEANANCHOR MARITIME LIMITED | | | SCAC4 |
| 12 | OCNI | OCONNOR PETROLEUM TRUCKING INC | | | SCAC3 |
| 13 | OCNJ | OIL CITY PETROLEUM | | | SCAC4 |
| 14 | OCNK | OCEAN KNIGHT SHIPPING INC | | | SCAC4 |
| 15 | OCNM | OCONNELLS MOVING SERVICE | | | SCAC3 |
| 16 | OCNM | ONTARIO CABINET MAKERS | | | SCAC4 |
| 17 | OCNO | OCONNOR CHARTER & TOURS SERVICE | | | SCAC3 |
| 18 | OCNQ | OCEANSIDE HARBOR TRANSFER CO INC | | | SCAC3 |
| 19 | OCNR | OCONNER TRUCKING CO | | | SCAC3 |
| 20 | OCNR | OCEANARIUM SHIPPING LIMITED | | | SCAC4 |
| 21 | OCNS | OCEANIC CONTAINER SERVICE INC | | | SCAC3 |
| 22 | OCNS | OCEANPORT LLC | | | SCAC4 |
| 23 | OCNT | OCONNOR, THOMAS V TRUCKING | | | SCAC3 |
| 24 | OCNU | OCEANIC CONTAINERS, LLC | | USA | BIC |
| 25 | OCNU | OCEAN LINES INC. | | | PWRC |
| 26 | OCNU | Ocean Lines | | | RSRV |
| 27 | OCNU | OCEAN LINE INC | | | SCAC3 |
| 28 | OCNU | OCEAN LINE INC | | | SCAC4 |
| 29 | OCNW | OCEANWAY TRANSPORT INC | | | SCAC3 |
