| Carrier Code | Carrier Name |
| OSHL | ONDINA SHIPPING COMPANY LIMITED |
| OSHP | OCEAN SHIPS INC |
| OSLU | OCEAN STAR LINE A D |
| OSNV | OPAL SEAS NAVIGATION LTD |
| OSSA | OLYMPIC STEAMSHIP AGENCIES INC |
| OSSU | OSSBORN B V |
| OTAU | OT AFRICA LINE LTD |
| OTH0 | |
| OTLU | ORIENT TAINERS PTE LTD |
| OTNG | OTTINGER, JAY |
| OTUS | ODFJELL TANKERS (USA) INC |
| OUAK | OUTDOOR ALASKA |
| OVBK | OVERSEAS BULKTANK CORPORATION |
| OVCU | OVERSEAS CONTAINERS LIMITED |
| OVEN | OVERSEAS ENTERPRISES INC |
