| 1 | OAL | Olympic Airways | IATA: OA, Callsign: Olympic, IATA Prefix: 050, Name changed to Olympic Airlines | GR | AVCODES |
| 2 | OAL | Olympic Airlines | IATA: OA, Callsign: Olympic, IATA Prefix: 050, IATA designator changed to OP. Name changed from Olympic Airways | GR | AVCODES |
| 3 | OAL | Olympic Airlines | IATA: OP, Callsign: Olympic, IATA Prefix: 050, IATA designator changed from OA. Name changed from Olympic Airways | GR | AVCODES |
| 4 | OAL | Olympic Air | IATA: OA, Callsign: Olympic, IATA Prefix: 050, | GR | AVCODES |
| 5 | OAL | Olympic Airlines | IATA: OA | | ICAO1 |
| 6 | OALU | OCEAN AFRICA CONTAINER LINE PTY LTD | | | SCAC4 |
| 7 | OALX | Oregon-American Lumber Corp. | 7/1937-1/1952; eliminated 1/1953 | | NAKINA |
| 8 | OALX | Oregon-American Lumber Corp. | 4/38-1/52; eliminated 1/53 | | NRHS |
| 9 | OALX | OREGON-AMERICAN LUMBER CORP. | | | PWRC |