| 1 | OLY | Olympic Aviation, S.A. | IATA: ML, Callsign: Olavia, Designator ML* recalled by IATA. Founded in 1971. Ceased operation in 2003. | GR | AVCODES |
| 2 | OLY | Olympus Airways | Callsign: Oly Air, | GR | AVCODES |
| 3 | OLY | Olympic Aviation | | | ICAO1 |
| 4 | OLYA | OLYMPIA TILE | | | SCAC4 |
| 5 | OLYC | OLYMPIC FLAME FUEL OIL CO INC | | | SCAC4 |
| 6 | OLYF | OLYMPIC FOODS INC | | | SCAC3 |
| 7 | OLYG | SHOWA LINE, LTD. | | | PWRC |
| 8 | OLYG | OLYMPIC-GRIFFITHS LINES INC | | | SCAC3 |
| 9 | OLYI | OLYMPIC TRANSIT INC | | | SCAC3 |
| 10 | OLYK | OLINYK TRUCKING LTD | | | SCAC3 |
| 11 | OLYM | OLYMPIC FILM SERVICE INC | | | SCAC3 |
| 12 | OLYM | OLYMPIC OIL COMPANY | | | SCAC4 |
| 13 | OLYMP | Olympus Bus & Coach Limited | | GB | TRAFFIC |
| 14 | OLYMPIA | Olympia Trails | A Coach USA company | USA | TRAFFIC |
| 15 | OLYN | OLYMPIA NAVIGATION LIMITED | | | SCAC4 |
| 16 | OLYP | OLYMPIC PIPE LINE COMPANY | | | SCAC3 |
| 17 | OLYQ | O LEARYS EXPRESS | | | SCAC3 |
| 18 | OLYR | The Olympic R.R. Co. | added 7/1989; 1/1994-7/2005 | | NAKINA |
| 19 | OLYR | The Olympic R.R. Co. | added 7/89; 1/94-7/2000 | | NRHS |
| 20 | OLYR | OLYMPIC RAILROAD COMPANY | | | PWRC |
| 21 | OLYR | Olympic Railroad | | | RSRV |
| 22 | OLYR | Olympic Railroad | | | RSRV |
| 23 | OLYR | OLYMPIC RAILROAD CO, THE | | | SCAC3 |
| 24 | OLYR | OLYMPIC RAILROAD CO, THE | | | SCAC4 |
| 25 | OLYU | OLYMPIC CONTAINER CORPORATION | | | PWRC |
| 26 | OLYU | Olympic Container Corporation | | | RSRV |
| 27 | OLYU | OLYMPIC CONTAINER CORP. | | | SCAC3 |
| 28 | OLYW | OLYMPIC WOOD PRODUCTS INC | | | SCAC3 |
| 29 | OLYX | Olympia Petroleum, Inc. | added 7/1980; eliminated 10/1985 | | NAKINA |
| 30 | OLYX | Olympia Petroleum, Inc. | added 7/80 | | NRHS |
| 31 | OLYX | OLYMPIA PETROLEUM, INC. | | | PWRC |
| 32 | OLYX | Olympia Petroleum | | | RSRV |
| 33 | OLYZ | SHOWA LINE, LTD. | | | PWRC |
| 34 | OLYZ | Showa Line | | | RSRV |
| 35 | OLYZ | SHOWA LINE, LTD. | | | SCAC4 |
