| 1 | OR | Crimea Air | ICAO: CRF, Callsign: Crimea Air, IATA Prefix: 107, Name changed to KRYM, Limited Partnership International Airline. Designator OR* reinstated by IATA | UA | AVCODES |
| 2 | OR | Crimea Air | ICAO: CRF, Callsign: Crimea Air, IATA Prefix: 107, Designator OR* recalled by IATA | UA | AVCODES |
| 3 | OR | Air Comores | Callsign: Aircomor, Designator OR recalled by IATA | COM | AVCODES |
| 4 | OR | TUI Airlines Nederlands B.V. t/a Arkefly | ICAO: TFL, Callsign: Arkefly, Name changed to TUI Airlines Nederlands B.V. t/a Arke w.e.f. 01 October 2013. ICAO callsign changed to Orange. | NL | AVCODES |
| 5 | OR | TUI Airlines Nederlands B.V. t/a Arke | ICAO: TFL, Callsign: Orange, Name changed from TUI Airlines Nederlands B.V. t/a Arkefly w.e.f. 01 October 2013. ICAO callsign changed from Arkefly. | NL | AVCODES |
| 6 | OR | TUI Airlines Nederlands B.V. t/a TUI fly Netherlands | ICAO: TFL, Callsign: Orange, Name changed from TUI Airlines Nederlands B.V. t/a Arke w.e.f. 01 October 2015. ICAO callsign changed from Arkefly. | NL | AVCODES |
| 7 | OR | Owasco River | 1/1975-1/1980 | | NAKINA |
| 8 | OR | Owasco River | 1/75-1/80 | | NRHS |
| 9 | OR | *OAHU RAILWAY, INC. | | | PWRC |
| 10 | OR | *OWASCO RIVER RAILWAY | | | PWRC |
| 11 | OR | Owasco River Railway | | | RSRV |
| 12 | ORA | Montauk Caribbean Airways, Inc. d/b/a Long Island Airlines | Callsign: Long Island, | USA | AVCODES |
| 13 | ORA | Long Island Airlines | | | ICAO1 |
| 14 | ORA | Ormet R.R. Corp. | 7/2000-7/2005 | | NAKINA |
| 15 | ORA | Ormet R.R. Corp. | Jul-00 | | NRHS |
| 16 | ORA | ORMET RAILROAD CORP. | | | PWRC |
| 17 | ORA | Ormet Railroad | | | RSRV |
| 18 | ORAC | ORANGE COUNTY DELIVERY SERVICE INC | | | SCAC4 |
| 19 | ORAD | ORCON DE MEXICO S A DE C V | | | SCAC4 |
| 20 | ORAG | ORSAG TRUCKING | | | SCAC4 |
| 21 | ORAN | ORANGE TERMINAL | | | PWRC |
| 22 | ORAN | ORANGE EMPIRE TRUCK LINES, INC | | | SCAC3 |
| 23 | ORAN | ORANGE TKO | | | SCAC4 |
| 24 | ORAU | INTERMODAL LOGISTICS PLUS LLC | | RUS | BIC |
| 25 | ORAU | ORIENT AUSTRALIA PTY LTD | | | SCAC4 |
| 26 | ORB | Orenburg Airlines Federal State Unitary Enterprise | {IATA: R2, Callsign: Orenburg, IATA Prefix: 291, Name changed to JSC "Orenburg Airlines". Name changed from State Unitary Avia Enterprise d/b/a Orenburg Airlines. Designator R2 reinstated by IATA};SRCKEY=AVCODES | RUS | |
| 27 | ORB | JSC "Orenburg Airlines" | {IATA: R2, Callsign: Orenburg, IATA Prefix: 291, Merged into Rossiya Airlines JSC (FV/SDM) w.e.f. 26 May 2016. Name changed to JSC "Orenburg Airlines". Name changed from State Unitary Avia Enterprise d/b/a Orenburg Airlines. Designator R2 reinstated by IATA};SRCKEY=AVCODES | RUS | |
| 28 | ORB | State Unitary Avia Enterprise d/b/a Orenburg Airlines | IATA: R2, Callsign: Orenburg, IATA Prefix: 291, Name changed to Orenburg Airlines Federal State Unitary Enterprise | RUS | AVCODES |
| 29 | ORB | Orenburg Airlines | IATA: R2 | | ICAO1 |
| 30 | ORB | ORANGE BELT STAGES | | | SCAC4 |
| 31 | ORBA | ORBITRANS AIR FREIGHT INC | | | SCAC3 |
| 32 | ORBC | ORBCO | | | SCAC3 |
| 33 | ORBI | ORBITAL TRANSPORT INC | | | SCAC3 |
| 34 | ORBIS | Orbis Interntional | Orbis International is an international non-profit non-governmental organization (NGO) dedicated to saving sight worldwide.[ | USA | TRAFFIC |
| 35 | ORBM | ORMSBY & BAUMEZ JR | | | SCAC3 |
| 36 | ORBN | ORBIT TRANSPORT & STORAGE INC | | | SCAC3 |
| 37 | ORBN | ORBIS EXPRESS INC | | | SCAC4 |
| 38 | ORBO | ORTON, BOB TRUCKING | | | SCAC4 |
| 39 | ORBQ | ORBIT MOVING & STORAGE INC | | | SCAC3 |
| 40 | ORBQ | ORBIT MOVING & STORAGE INC | | | SCAC4 |
| 41 | ORBT | Orbis Travel | | PL | TRAFFIC |
| 42 | ORBU | ORBIT CHEMICAL INDUSTRIES LIMITED | | EAK | BIC |
| 43 | ORBU | ENTERPRISE CONTAINER LINES | | | SCAC3 |
| 44 | ORBU | ORBIT CHEMICAL INDUSTRIES LTD | | | SCAC4 |
| 45 | ORBY | ORMSBY TRUCKING INC | | | SCAC3 |
| 46 | ORBY | ORMSBY TRUCKING INC | | | SCAC4 |
| 47 | ORC | Air Cordial Limited | Callsign: Cordiale, | GB | AVCODES |
| 48 | ORC | Oriental Air Bridge Co. Ltd. | IATA: OC, Callsign: Oriental Bridge, IATA designator changed from O3. ICAO Designator changed to NGK. | J | AVCODES |
| 49 | ORC | OGEECHEE RAILROAD CO. | | | PWRC |
| 50 | ORC | OGEECHEE RAILROAD COMPANY | | | SCAC4 |
| 51 | ORC | Oriental Air Bridge | | J | TRAFFIC |
| 52 | ORCA | ORCAS ISLAND FREIGHT LINES, INC | | | SCAC3 |
| 53 | ORCA | ORCAS ISLAND FREIGHT LINES INC | | | SCAC4 |
| 54 | ORCD | ORCHARD TRANSPORT LTD | | | SCAC3 |
| 55 | ORCD | ORCHARD TRANSPORT LTD | | | SCAC4 |
| 56 | ORCF | ORCHARD HILL FARMS INC | | | SCAC4 |
| 57 | ORCK | O R TRUCKING | | | SCAC3 |
| 58 | ORCL | ORACLE TRANSPORT INC | | | SCAC4 |
| 59 | ORCN | OIL RE-REFINING CO INC | | | SCAC4 |
| 60 | ORCO | OHIO RIVER COMPANY, THE | | | SCAC3 |
| 61 | ORCQ | ORICA LINES | | | SCAC3 |
| 62 | ORCS | ORCAL TRANSPORT SERVICES INCORPORAT | | | SCAC3 |
| 63 | ORCT | ORILLIA CITY TRUCKLINES LTD | | | SCAC3 |
| 64 | ORCU | ORCA CONTAINER ASSET MANAGEMENT | | ZA | BIC |
| 65 | ORCU | BSL TRANSPORT | | | PWRC |
| 66 | ORCU | BSL Transport | | | RSRV |
| 67 | ORCU | ORCA CONTAINER ASSET MANAGEMENT | | | SCAC4 |
| 68 | ORCX | Oklahoma Refining Co. | 7/1937-4/1938 | | NAKINA |
| 69 | ORCX | The Neatesfoot Oil Refineries Corp. | 7/1935 | | NAKINA |
| 70 | ORCX | Oklahoma Refining Co. | Apr-38 | | NRHS |
| 71 | ORCX | OKLAHOMA REFINING CO. | | | PWRC |
| 72 | ORCZ | OHIO RIVER COMPANY | | | PWRC |
| 73 | ORD | Cap. P.A. Hernando R. Ordonez Gutierrez | Callsign: Ordonez, | MEX | AVCODES |
| 74 | ORD | Orange Air Services | | | ICAO1 |
| 75 | ORDB | ORANGE DISTRIBUTION INC | | | SCAC3 |
| 76 | ORDC | OROURKE DISTRIBUTING CO | | | SCAC3 |
| 77 | ORDJ | ORANGE TRUCKING INC | | | SCAC3 |
| 78 | ORDL | ORDER SHIPPING LIMITED | | | SCAC3 |
| 79 | ORDL | ORDILLE, P N INC | | | SCAC4 |
| 80 | ORDT | ORCUTT, DUANE TRUCKING | | | SCAC3 |
| 81 | ORDW | ORDWAY TRUCKING | | | SCAC3 |
| 82 | ORE | Greendale Aviation Company Ltd. | Callsign: Rekoya, | WAN | AVCODES |
| 83 | ORE | Orange Aviation | | | ICAO1 |
| 84 | OREC | OMEGA RECICLYNG | | | SCAC4 |
| 85 | OREE | ORIENTAL EXPRESS | | | SCAC3 |
| 86 | OREG | OREGRO SEEDS INC | | | SCAC4 |
| 87 | OREK | OAK RIDGES ENTERPRISES INC | | | SCAC4 |
| 88 | OREN | ORENELAS ARMENTA, PABLO | | | SCAC4 |
| 89 | OREN | | City: Orenburg | RUS | TRAFFIC |
| 90 | OREQ | OREGON TRUCK LINE | | | SCAC3 |
| 91 | ORER | ORNELAS RIVERA, JOSE DE JESUS | | | SCAC4 |
| 92 | ORET | OREGON TRANSFER CO | | | SCAC3 |
| 93 | ORET | OREGON TRANSFER CO | | | SCAC4 |
| 94 | OREU | ORIENT EXPRESS LLC | | RUS | BIC |
| 95 | OREU | ORIENT EXPRESS LLC | | | SCAC4 |
| 96 | OREX | Oregon Dept. of Agriculture | 1/1994-7/2005 (not listed) | | NAKINA |
| 97 | OREX | REA Express, Inc. | added 10/1970; added 1/1971; eliminated 4/1974 | | NAKINA |
| 98 | OREX | REA Express, owned and operated by Railway Express Agency, Inc. | eliminated 1/1971 | | NAKINA |
| 99 | OREX | REA Express | added 10/1970 | | NAKINA |
| 100 | OREX | Omaha Refining Co. | 8/1920 | | NAKINA |
